Update protos and add builder shim version in Package.swift (#176)

This PR updates the protos to match the recent changes in
https://github.com/apple/container-builder-shim/pull/15.

This PR additionally adds the builder shim version as a variable in
Package.swift. This allows us to be consistent with the builder tag used
for the builder shim image and when building protobuf files.

Signed-off-by: Kathryn Baldauf <k_baldauf@apple.com>

Sources/CVersion/Version.c

@@ -42,3 +42,7 @@ const char* get_release_version() {
 const char* get_swift_containerization_version() {
     return CZ_VERSION;
 }
+
+const char* get_container_builder_shim_version() {
+    return BUILDER_SHIM_VERSION;
+}

Sources/CVersion/include/Version.h

@@ -40,8 +40,14 @@
 #define RELEASE_VERSION "0.0.0"
 #endif
 
+#ifndef BUILDER_SHIM_VERSION
+#define BUILDER_SHIM_VERSION "0.0.0"
+#endif
+
 const char* get_git_commit();
 
 const char* get_release_version();
 
 const char* get_swift_containerization_version();
+
+const char* get_container_builder_shim_version();