Make TestContext.RegisterModuleType take an android.ModuleFactory

Avoid having to pass ModuleFactoryAdaptor to every call to
RegisterModuleType in a test by wrapping RegisterModuleType.

Test: all soong tests
Change-Id: If8847d16487de0479cc3020b728256922b3cadba
diff --git a/android/prebuilt_test.go b/android/prebuilt_test.go
index 0a18e2c..81fb278 100644
--- a/android/prebuilt_test.go
+++ b/android/prebuilt_test.go
@@ -132,9 +132,9 @@
 			ctx := NewTestContext()
 			ctx.PreArchMutators(RegisterPrebuiltsPreArchMutators)
 			ctx.PostDepsMutators(RegisterPrebuiltsPostDepsMutators)
-			ctx.RegisterModuleType("filegroup", ModuleFactoryAdaptor(FileGroupFactory))
-			ctx.RegisterModuleType("prebuilt", ModuleFactoryAdaptor(newPrebuiltModule))
-			ctx.RegisterModuleType("source", ModuleFactoryAdaptor(newSourceModule))
+			ctx.RegisterModuleType("filegroup", FileGroupFactory)
+			ctx.RegisterModuleType("prebuilt", newPrebuiltModule)
+			ctx.RegisterModuleType("source", newSourceModule)
 			ctx.Register()
 			ctx.MockFileSystem(map[string][]byte{
 				"prebuilt_file": nil,