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/licenses.go b/android/licenses.go
index bd14b26..81c557e 100644
--- a/android/licenses.go
+++ b/android/licenses.go
@@ -303,6 +303,7 @@
 	switch reflect.TypeOf(module).String() {
 	case "*android.licenseModule": // is a license, doesn't need one
 	case "*android.licenseKindModule": // is a license, doesn't need one
+	case "*android.genNoticeModule": // contains license texts as data
 	case "*android.NamespaceModule": // just partitions things, doesn't add anything
 	case "*android.soongConfigModuleTypeModule": // creates aliases for modules with licenses
 	case "*android.soongConfigModuleTypeImport": // creates aliases for modules with licenses