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.

Bug: 296873595
Change-Id: Ic2e43aa9b161231fea4416d1f0d36b778361d7c5
diff --git a/testing/Android.bp b/testing/Android.bp
index 18dccb3..43040b0 100644
--- a/testing/Android.bp
+++ b/testing/Android.bp
@@ -8,11 +8,14 @@
     deps: [
         "blueprint",
         "soong-android",
+        "soong-testing-code_metadata_internal_proto",
         "soong-testing-test_spec_proto",
 
     ],
     srcs: [
+        "all_code_metadata.go",
         "all_test_specs.go",
+        "code_metadata.go",
         "test_spec.go",
         "init.go",
         "test.go",