Add a String() method to android.Module

Add a String() method to android.Module for use in debugging.  Store
the name and variations of the module as they are mutated.

Test: TestModuleString
Bug: 136473661
Change-Id: I74e393703dcfc96ed4e21ac4a4419a7858b59216

android/hooks.go

@@ -129,6 +129,8 @@ func registerLoadHookMutator(ctx RegisterMutatorsContext) {
 
 func LoadHookMutator(ctx TopDownMutatorContext) {
 	if m, ok := ctx.Module().(Module); ok {
+		m.base().commonProperties.DebugName = ctx.ModuleName()
+
 		// Cast through *topDownMutatorContext because AppendProperties is implemented
 		// on *topDownMutatorContext but not exposed through TopDownMutatorContext
 		var loadHookCtx LoadHookContext = ctx.(*topDownMutatorContext)