[REQUEST] Support for overlaying or building with mms configs

[RealJohnGalt]

It would be nice if there could be support for easily building with mms configs (eg: https://github.com/GrapheneOS/platform_packages_apps_Messaging/commit/18282a3fb8fa8fd13f84f40857ab904645550747)

Many users cannot use third party messaging apps due to obscure mms breakages on third party apps (and google assumes everyone uses google messages so doesn't have a platform implementation for shipping them globally).