Update project structure and dependencies

[friederbluemle]

This is a full project update and partial cleanup, making the project compatible with the latest version of Android Studio, and the latest build tools/dependencies.

It also enables a very basic GitHub Actions based CI (just running ./gradlew build).

Example of a successful build: https://github.com/friederbluemle/video-enabled-webview/runs/524897949

Includes, supersedes, and closes #45

_{^{Once approved, please use a normal GitHub merge (i.e. NO rebase/squash merge) to integrate the commit(s) from the PR head branch. The changes are broken up into meaningful, atomic commits, and my branch should already be up-to-date with the latest base branch. If it isn't, or if you want me to change anything, please let me know, and I will update the branch as soon as possible. Thank you!}}

[netineti0]

can we merge this?

[friederbluemle]

can we merge this?

@animesh-sharama I wish we could, but I don't have write access to this repo. The last commit on master was created 3 years ago, so the repo looks pretty inactive to me. If you want a copy with all these updates, you can download it directly from my fork: https://github.com/friederbluemle/video-enabled-webview/archive/update-project.zip