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

bpf/bpf_test.go

@@ -58,9 +58,9 @@ func testConfig(buildDir string, env map[string]string, bp string) android.Confi
 }
 
 func testContext(config android.Config) *android.TestContext {
-	ctx := cc.CreateTestContext()
+	ctx := cc.CreateTestContext(config)
 	ctx.RegisterModuleType("bpf", BpfFactory)
-	ctx.Register(config)
+	ctx.Register()
 
 	return ctx
 }