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/python/python_test.go b/python/python_test.go
index e5fe126..ba5e7fa 100644
--- a/python/python_test.go
+++ b/python/python_test.go
@@ -332,12 +332,9 @@
 			ctx.PreDepsMutators(func(ctx android.RegisterMutatorsContext) {
 				ctx.BottomUp("version_split", versionSplitMutator()).Parallel()
 			})
-			ctx.RegisterModuleType("python_library_host",
-				android.ModuleFactoryAdaptor(PythonLibraryHostFactory))
-			ctx.RegisterModuleType("python_binary_host",
-				android.ModuleFactoryAdaptor(PythonBinaryHostFactory))
-			ctx.RegisterModuleType("python_defaults",
-				android.ModuleFactoryAdaptor(defaultsFactory))
+			ctx.RegisterModuleType("python_library_host", PythonLibraryHostFactory)
+			ctx.RegisterModuleType("python_binary_host", PythonBinaryHostFactory)
+			ctx.RegisterModuleType("python_defaults", defaultsFactory)
 			ctx.PreArchMutators(android.RegisterDefaultsPreArchMutators)
 			ctx.Register()
 			ctx.MockFileSystem(d.mockFiles)