Script for adding git tags for each release

It is useful to tag commits for each androidx release for the following reasons:

• This places the release history into the commit history.
• Developers can find which commits were included within each artifact version.
• Tags are easy references for diff-ing two versions of an artifact.

This script takes in a file that lists the commits, artifacts, and versions of that release. A new release file must be added along with every release. These files have the following filename format: AndroidX-Release-YYYY-MM-DD.txt, where YYYY-MM-DD is the release date.

And have the following scructure: <Release Date in YYYY-MM-DD format> <SHA>:<artifactId>:<version> <SHA>:<artifactId>:<version> . . . <SHA>:<artifactId>:<version>

The script then uses this file to generate two tags for each SHA in the file. This first tag is maps the commit to the release date and artifactId: <YYYY-MM-DD>-release-<artifactId> The second tag maps the commit to the artifact version. This is the last commit included with that version (inclusive cuttoff): <artifactId>-<version>