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
diff --git a/bp2build/testing.go b/bp2build/testing.go
index faf1a44..266b817 100644
--- a/bp2build/testing.go
+++ b/bp2build/testing.go
@@ -140,16 +140,6 @@
 	customBazelModuleAttributes
 }
 
-func customBazelModuleFactory() android.Module {
-	module := &customBazelModule{}
-	module.AddProperties(&module.customBazelModuleAttributes)
-	android.InitBazelTargetModule(module)
-	return module
-}
-
-func (m *customBazelModule) Name() string                                          { return m.BaseModuleName() }
-func (m *customBazelModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {}
-
 func customBp2BuildMutator(ctx android.TopDownMutatorContext) {
 	if m, ok := ctx.Module().(*customModule); ok {
 		if !m.ConvertWithBp2build(ctx) {
@@ -178,7 +168,7 @@
 			Rule_class: "custom",
 		}
 
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, m.Name(), props, attrs)
+		ctx.CreateBazelTargetModule(m.Name(), props, attrs)
 	}
 }
 
@@ -197,19 +187,19 @@
 			Rule_class:        "my_library",
 			Bzl_load_location: "//build/bazel/rules:rules.bzl",
 		}
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName, myLibraryProps, attrs)
+		ctx.CreateBazelTargetModule(baseName, myLibraryProps, attrs)
 
 		protoLibraryProps := bazel.BazelTargetModuleProperties{
 			Rule_class:        "proto_library",
 			Bzl_load_location: "//build/bazel/rules:proto.bzl",
 		}
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName+"_proto_library_deps", protoLibraryProps, attrs)
+		ctx.CreateBazelTargetModule(baseName+"_proto_library_deps", protoLibraryProps, attrs)
 
 		myProtoLibraryProps := bazel.BazelTargetModuleProperties{
 			Rule_class:        "my_proto_library",
 			Bzl_load_location: "//build/bazel/rules:proto.bzl",
 		}
-		ctx.CreateBazelTargetModule(customBazelModuleFactory, baseName+"_my_proto_library_deps", myProtoLibraryProps, attrs)
+		ctx.CreateBazelTargetModule(baseName+"_my_proto_library_deps", myProtoLibraryProps, attrs)
 	}
 }