cli: Add support for --stop-signal (#1462)

- Closes #1581.
- This adds stop signal support to the cli. The priority is:
  1. If an explicit stop signal is passed on the cli use this.
  2. If not, check if there is a stop signal in the image config.
  3. Finally, use the default (TERM).

Sources/ContainerCommands/Container/ContainerStop.swift

@@ -19,7 +19,6 @@ import ContainerAPIClient
 import ContainerResource
 import Containerization
 import ContainerizationError
-import ContainerizationOS
 import Foundation
 import Logging
 
@@ -35,7 +34,7 @@ extension Application {
         var all = false
 
         @Option(name: .shortAndLong, help: "Signal to send to the containers")
-        var signal: String = "SIGTERM"
+        var signal: String?
 
         @Option(name: .shortAndLong, help: "Seconds to wait before killing the containers")
         var time: Int32 = 5
@@ -68,7 +67,7 @@ extension Application {
 
             let opts = ContainerStopOptions(
                 timeoutInSeconds: self.time,
-                signal: try Signal(self.signal).rawValue
+                signal: self.signal
             )
             try await Self.stopContainers(
                 client: client,