Add support for armeabi-v7a devices

[Ahmed-762]

I mean that the application does not work on my device. It works with architecture armeabi-v7a

[syntaxerror247]

The app currently only supports arm64-v8a devices.

Since you mentioned in the title that you'd like to add support for this, here are the things that need to be done:

1. Build rootfs for armeabi-v7a.
2. Build proot for armeabi-v7a as well. See Build proot for x86_64 as well #20 for reference.
3. Update app gradle file.