Add support to cache AVD in github workflow

[snaik20]

Checklist

• [X] I made sure that there are no existing issues - open or closed - which I could contribute my information to.
• [X] I have read the FAQ and my problem isn't listed.
• [X] I'm aware that this is a request for NewPipe itself and that requests for adding a new service need to be made at NewPipeExtractor.
• [X] I have taken the time to fill in all the required details. I understand that the feature request will be dismissed otherwise.
• [X] This issue contains only one feature request.
• [X] I have read and understood the contribution guidelines.

Feature description

Add support to cache the AVDs used in the github workflows. This will reduce the startup time in the android tests workflow.

Why do you want this feature?

Improves the time required to run the gihub checks.

Additional information

https://github.com/marketplace/actions/android-emulator-runner#usage--examples