Add bazel staging mode to soong build.

This is to use bazel to build targets that are being prepared for an
incipient release to the prod mode allowlist.

Bug: 254265047
Test: m nothing
Test: m nothing --bazel-mode-dev
Test: m nothing --bazel-mode-staging
Change-Id: Ic78a59cf51dba83ef1ac26483586560ea9b24aaf

cmd/soong_build/main.go

@@ -88,6 +88,7 @@ func init() {
 	flag.StringVar(&cmdlineArgs.OutFile, "o", "build.ninja", "the Ninja file to output")
 	flag.BoolVar(&cmdlineArgs.EmptyNinjaFile, "empty-ninja-file", false, "write out a 0-byte ninja file")
 	flag.BoolVar(&cmdlineArgs.BazelMode, "bazel-mode", false, "use bazel for analysis of certain modules")
+	flag.BoolVar(&cmdlineArgs.BazelMode, "bazel-mode-staging", false, "use bazel for analysis of certain near-ready modules")
 	flag.BoolVar(&cmdlineArgs.BazelModeDev, "bazel-mode-dev", false, "use bazel for analysis of a large number of modules (less stable)")
 
 	// Flags that probably shouldn't be flags of soong_build but we haven't found
@@ -142,6 +143,8 @@ func newConfig(availableEnv map[string]string) android.Config {
 		buildMode = android.BazelDevMode
 	} else if cmdlineArgs.BazelMode {
 		buildMode = android.BazelProdMode
+	} else if cmdlineArgs.BazelModeStaging {
+		buildMode = android.BazelStagingMode
 	} else {
 		buildMode = android.AnalysisNoBazel
 	}