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
diff --git a/java/hiddenapi_singleton_test.go b/java/hiddenapi_singleton_test.go
index 7acaae7..34a4856 100644
--- a/java/hiddenapi_singleton_test.go
+++ b/java/hiddenapi_singleton_test.go
@@ -29,8 +29,8 @@
 	return config
 }
 
-func testContextWithHiddenAPI() *android.TestContext {
-	ctx := testContext()
+func testContextWithHiddenAPI(config android.Config) *android.TestContext {
+	ctx := testContext(config)
 	ctx.RegisterSingletonType("hiddenapi", hiddenAPISingletonFactory)
 	return ctx
 }
@@ -38,7 +38,7 @@
 func testHiddenAPIWithConfig(t *testing.T, config android.Config) *android.TestContext {
 	t.Helper()
 
-	ctx := testContextWithHiddenAPI()
+	ctx := testContextWithHiddenAPI(config)
 
 	run(t, ctx, config)
 	return ctx