Pass Config to NewTestContext instead of ctx.Register

Prepare for using Config when adding singletons by passing
Config to NewTestContext and NewContext instead of to ctx.Register.
This will enable a followup change to store SingletonMakeVarsProviders
registered on the Context in the Config, which is necessary to run
multiple tests in parallel without data races.

Test: all soong tests
Change-Id: Id229629a4e42ff4487d317241673837726c075fc

android/path_properties_test.go

@@ -116,12 +116,12 @@ func TestPathDepsMutator(t *testing.T) {
 			`
 
 			config := TestArchConfig(buildDir, nil, bp, nil)
-			ctx := NewTestArchContext()
+			ctx := NewTestArchContext(config)
 
 			ctx.RegisterModuleType("test", pathDepsMutatorTestModuleFactory)
 			ctx.RegisterModuleType("filegroup", FileGroupFactory)
 
-			ctx.Register(config)
+			ctx.Register()
 			_, errs := ctx.ParseFileList(".", []string{"Android.bp"})
 			FailIfErrored(t, errs)
 			_, errs = ctx.PrepareBuildActions(config)