Mobile configuration for Thunderbird

Similar to mobile-config-firefox, but for Thunderbird.

Screenshots

See repository: https://gitlab.postmarketos.org/DylanVanAssche/mobile-config-thunderbird#screenshots

How to test

1. Install Thunderbird: doas apk add thunderbird
2. Install the mobile-config-thunderbird package
3. Launch Thunderbird

Would be great if we can move it under the pmOS umbrella like mobile-config-firefox.