Don't create a new module for bp2build conversion.

A performance improvement for bp2build as Blueprint/Soong no longer have
the overhead of additional modules. The creation of these modules
results in:
* traversal of additional modules for each subsequent mutator
* synchronization over a go channel to collect newly created modules:
https://cs.android.com/android/platform/superproject/+/master:build/blueprint/context.go;l=2594,2600;drc=1602226f23181b8c3fbfcaf3358f0297e839d7d3

We avoid both of these by storing the information directly in the
underlying module.

Also as a fringe benefit, removes some necessary boilerplate for
conversion.

For benchmarks, reduces runtime ~1% for 1% converted, ~24% for 100%
converted. See more: go/benchmarks-for-https:-r.android.com-1792714

Test: ran benchmarks/tests in bp2build
Test: build/bazel/ci/bp2build.sh
Change-Id: Ie9273b8cbab5bc6edac1728067ce184382feb211

android/filegroup.go

@@ -34,24 +34,6 @@ type bazelFilegroupAttributes struct {
 	Srcs bazel.LabelListAttribute
 }
 
-type bazelFilegroup struct {
-	BazelTargetModuleBase
-	bazelFilegroupAttributes
-}
-
-func BazelFileGroupFactory() Module {
-	module := &bazelFilegroup{}
-	module.AddProperties(&module.bazelFilegroupAttributes)
-	InitBazelTargetModule(module)
-	return module
-}
-
-func (bfg *bazelFilegroup) Name() string {
-	return bfg.BaseModuleName()
-}
-
-func (bfg *bazelFilegroup) GenerateAndroidBuildActions(ctx ModuleContext) {}
-
 func FilegroupBp2Build(ctx TopDownMutatorContext) {
 	fg, ok := ctx.Module().(*fileGroup)
 	if !ok || !fg.ConvertWithBp2build(ctx) {
@@ -69,7 +51,7 @@ func FilegroupBp2Build(ctx TopDownMutatorContext) {
 		Bzl_load_location: "//build/bazel/rules:filegroup.bzl",
 	}
 
-	ctx.CreateBazelTargetModule(BazelFileGroupFactory, fg.Name(), props, attrs)
+	ctx.CreateBazelTargetModule(fg.Name(), props, attrs)
 }
 
 type fileGroupProperties struct {