Inject OpenGApps to every container

[MrMcGoats]

🚀 Feature Request

Idea: Inject OpenGApps to every container, so that users have access to things like the Google Play Store.

Problems that want to be solved: User's currently don't have access to any GApps, most importantly, Google Play Store.

Note:
The thing preventing me from doing this is /system is mounted ro. We should probably inject OpenGApps during creation of the image itself anyway, so this feature should be implemented by modifying the Dockerfile.

I would like to just run the emulator with /system always mounted rw for now, since it makes testing way easier, but I can't find where the command that starts the emulator is, so I can't change it to mount /system rw.

/system can be mounted rw by passing the argument -e EMULATOR_ARGS="-writable-system" to the container.

/system is mounted rw by default, apparently, just need to run adb remount

[MrMcGoats]

Added a script to do this in 32506dd2cf75e8c1cb0fc505956a622670d189b6, but this should really be done either during container creation (ie. in the Dockerfile), or while the container is starting.

[MrMcGoats]

This should probably be done using a custom system image that already has OpenGApps injected, but this method will work for now.