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/csuite_config_test.go

@@ -21,9 +21,9 @@ import (
 func testCSuiteConfig(test *testing.T, bpFileContents string) *TestContext {
 	config := TestArchConfig(buildDir, nil, bpFileContents, nil)
 
-	ctx := NewTestArchContext()
+	ctx := NewTestArchContext(config)
 	ctx.RegisterModuleType("csuite_config", CSuiteConfigFactory)
-	ctx.Register(config)
+	ctx.Register()
 	_, errs := ctx.ParseFileList(".", []string{"Android.bp"})
 	FailIfErrored(test, errs)
 	_, errs = ctx.PrepareBuildActions(config)