Add a git tag and/or PR number to artifact and PR merge build filenames

[dhalbert]

When we merge a PR, firmware are uploaded to S3. Before that, artifacts are available.
The files have names like adafruit-circuitpython-8086_commander-en_GB-20230803-95c0867.uf2. This is not all that helpful. At the moment, when we are making both main and 8.2.x PR's, it would be nice if the names included the nearest tag and possibly the PR number.

[anecdata]

Seconded. PR would be particularly efficient for bisects.

[tannewt]

Version name is determined here: https://github.com/adafruit/circuitpython/blob/main/tools/build_board_info.py#L61

[dhalbert]

This worked for the PR builds, but the merge build has an incorrect name, e.g.
adafruit-circuitpython-8086_commander-de_DE-20231124-no-branch-3aac226.uf2. So needs more work.

[jepler]

The following git command will show the current branch name (or show "HEAD" if you currently have a 'detatched head'): git rev-parse --abbrev-ref HEAD

[dhalbert]

The following git command will show the current branch name (or show "HEAD" if you currently have a 'detatched head'): git rev-parse --abbrev-ref HEAD

I was doing something similar, but GITHUB_BASE_REF was the same thing. I expected that value to be available on the merge build, but apparently not. In addition, the PULL value appears to not be present, and I thought it was the same build step. I'll need to re-check those.