Set up GitHub Actions as CI/CD for Android Client

[Grandolf49]

Summary

We are planning to set up GitHub Actions as a CI/CD tool for all mobile repositories of Mifos. Creating this issue for tracking the progress on this.

Description

As mentioned by @edcable on the mailing lists, getting proper CI/CD for our mobile apps such that the community could easily generate APKs from the builds has been a long-standing priority and given the high degree of functionality and the seamless integration with Github, we have decided to use Github Actions vs Codeship, CircleCI, Travis which we had been using in past.