Rename CLI and ExecutableCLI folders (#635)

## Motivation and Context
This is an extension of #603 to cleanup the folder structure and have it
match with the new library and target names.

Sources/ContainerCommands/Registry/Login.swift

@@ -0,0 +1,93 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+import ContainerClient
+import Containerization
+import ContainerizationError
+import ContainerizationOCI
+import Foundation
+
+extension Application {
+    public struct Login: AsyncParsableCommand {
+        public init() {}
+        public static let configuration = CommandConfiguration(
+            abstract: "Login to a registry"
+        )
+
+        @Option(name: .shortAndLong, help: "Username")
+        var username: String = ""
+
+        @Flag(help: "Take the password from stdin")
+        var passwordStdin: Bool = false
+
+        @Argument(help: "Registry server name")
+        var server: String
+
+        @OptionGroup
+        var registry: Flags.Registry
+
+        public func run() async throws {
+            var username = self.username
+            var password = ""
+            if passwordStdin {
+                if username == "" {
+                    throw ContainerizationError(
+                        .invalidArgument, message: "must provide --username with --password-stdin")
+                }
+                guard let passwordData = try FileHandle.standardInput.readToEnd() else {
+                    throw ContainerizationError(.invalidArgument, message: "failed to read password from stdin")
+                }
+                password = String(decoding: passwordData, as: UTF8.self).trimmingCharacters(in: .whitespacesAndNewlines)
+            }
+            let keychain = KeychainHelper(id: Constants.keychainID)
+            if username == "" {
+                username = try keychain.userPrompt(domain: server)
+            }
+            if password == "" {
+                password = try keychain.passwordPrompt()
+                print()
+            }
+
+            let server = Reference.resolveDomain(domain: server)
+            let scheme = try RequestScheme(registry.scheme).schemeFor(host: server)
+            let _url = "\(scheme)://\(server)"
+            guard let url = URL(string: _url) else {
+                throw ContainerizationError(.invalidArgument, message: "Cannot convert \(_url) to URL")
+            }
+            guard let host = url.host else {
+                throw ContainerizationError(.invalidArgument, message: "Invalid host \(server)")
+            }
+
+            let client = RegistryClient(
+                host: host,
+                scheme: scheme.rawValue,
+                port: url.port,
+                authentication: BasicAuthentication(username: username, password: password),
+                retryOptions: .init(
+                    maxRetries: 10,
+                    retryInterval: 300_000_000,
+                    shouldRetry: ({ response in
+                        response.status.code >= 500
+                    })
+                )
+            )
+            try await client.ping()
+            try keychain.save(domain: server, username: username, password: password)
+            print("Login succeeded")
+        }
+    }
+}

Sources/ContainerCommands/Registry/Logout.swift

@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+import ContainerClient
+import Containerization
+import ContainerizationOCI
+
+extension Application {
+    public struct Logout: AsyncParsableCommand {
+        public init() {}
+        public static let configuration = CommandConfiguration(
+            abstract: "Log out from a registry")
+
+        @Argument(help: "Registry server name")
+        var registry: String
+
+        @OptionGroup
+        var global: Flags.Global
+
+        public func run() async throws {
+            let keychain = KeychainHelper(id: Constants.keychainID)
+            let r = Reference.resolveDomain(domain: registry)
+            try keychain.delete(domain: r)
+        }
+    }
+}

Sources/ContainerCommands/Registry/RegistryCommand.swift

@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+// Copyright © 2025 Apple Inc. and the container project authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//   https://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//===----------------------------------------------------------------------===//
+
+import ArgumentParser
+
+extension Application {
+    public struct RegistryCommand: AsyncParsableCommand {
+        public init() {}
+        public static let configuration = CommandConfiguration(
+            commandName: "registry",
+            abstract: "Manage registry configurations",
+            subcommands: [
+                Login.self,
+                Logout.self,
+            ],
+            aliases: ["r"]
+        )
+    }
+}