Add gen_notice module.

Refactor notices to support notices for multiple modules.

Enforce visibility and handle missing dependencies.

Bug: 213388645

Change-Id: Id6a81987f087419ad37d0cce57a71e8a7c4cd6e0
diff --git a/android/Android.bp b/android/Android.bp
index d583703..8eb55d2 100644
--- a/android/Android.bp
+++ b/android/Android.bp
@@ -49,6 +49,7 @@
         "expand.go",
         "filegroup.go",
         "fixture.go",
+        "gen_notice.go",
         "hooks.go",
         "image.go",
         "license.go",