Add combined_api_defaults module type

Allow specifying default combined api properties. This would be currently used to control the enablement of new mainline modules

Bug:b/289203818
Test: verified locally
Change-Id: I9415140453ce04efd5461cb8684c70e987810ecc
diff --git a/api/api.go b/api/api.go
index 2668999..43713aa 100644
--- a/api/api.go
+++ b/api/api.go
@@ -64,6 +64,7 @@
 
 type CombinedApis struct {
 	android.ModuleBase
+	android.DefaultableModuleBase
 
 	properties CombinedApisProperties
 }
@@ -74,6 +75,7 @@
 
 func registerBuildComponents(ctx android.RegistrationContext) {
 	ctx.RegisterModuleType("combined_apis", combinedApisModuleFactory)
+	ctx.RegisterModuleType("combined_apis_defaults", CombinedApisModuleDefaultsFactory)
 }
 
 var PrepareForCombinedApisTest = android.FixtureRegisterWithContext(registerBuildComponents)
@@ -409,6 +411,7 @@
 	module := &CombinedApis{}
 	module.AddProperties(&module.properties)
 	android.InitAndroidModule(module)
+	android.InitDefaultableModule(module)
 	android.AddLoadHook(module, func(ctx android.LoadHookContext) { module.createInternalModules(ctx) })
 	return module
 }
@@ -445,3 +448,16 @@
 	}
 	return s2
 }
+
+// Defaults
+type CombinedApisModuleDefaults struct {
+	android.ModuleBase
+	android.DefaultsModuleBase
+}
+
+func CombinedApisModuleDefaultsFactory() android.Module {
+	module := &CombinedApisModuleDefaults{}
+	module.AddProperties(&CombinedApisProperties{})
+	android.InitDefaultsModule(module)
+	return module
+}