Add Code Metadata rule to soong/testing.

This Cl adds a new rule to Soong to generate code ownership metadata. Also, this CL adds a provider in the Java SDK library to provide generated source files to the Code_metadata rule. Will add providers to other libraries in the future changes.

Ignore-AOSP-First: CPing test_spec rule to udc-mainline-prod to support migration of test targets. Cherry pick of:aosp/2786121

Bug: 296873595
Change-Id: Ic2e43aa9b161231fea4416d1f0d36b778361d7c5
Merged-In: Ic2e43aa9b161231fea4416d1f0d36b778361d7c5

android/source_file_provider.go

@@ -0,0 +1,11 @@
+package android
+
+import (
+	"github.com/google/blueprint"
+)
+
+type SrcsFileProviderData struct {
+	SrcPaths Paths
+}
+
+var SrcsFileProviderKey = blueprint.NewProvider(SrcsFileProviderData{})