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
diff --git a/android/allowlists/allowlists.go b/android/allowlists/allowlists.go
index 31368b2..6d3a63b 100644
--- a/android/allowlists/allowlists.go
+++ b/android/allowlists/allowlists.go
@@ -1347,4 +1347,8 @@
 	ProdMixedBuildsEnabledList = []string{
 		"com.android.adbd",
 	}
+
+	// Staging builds should be entirely prod, plus some near-ready ones. Add the
+	// new ones to the first argument as needed.
+	StagingMixedBuildsEnabledList = append([]string{}, ProdMixedBuildsEnabledList...)
 )