Support for GIthub Actions Jitconfig API

[acalejos]

First, let me start by saying thank you for this project! I've searched far and wide for a simple solution to this very problem, and had my first successful run using a self-hosted solution with a Mac Mini for my project

Since the newest release supports targeting the /repos endpoint and individual's projects rather than organizations, it might make sense to support the JIT config setup for Github Actions Runners. I ended up using a custom script provision using this endpoint along with ./run.sh --jitconfig {jitconfig} option.

So basically the command would look like:

jitconfig=$(curl -L \
  -X POST \
  -H "Accept: application/vnd.github+json" \
  -H "Authorization: Bearer <TOKEN with repo scope>" \
  -H "X-GitHub-Api-Version: 2022-11-28" \
  https://api.github.com/repos/OWNER/REPO/actions/runners/generate-jitconfig \
  -d '{"name":"{NAME_PARAM}-'$(uuidgen)'","runner_group_id":{RUNNER_GROUP},"labels":LABELS_ARRAY,"work_folder":{WORK_FOLDER}}' \
  | jq -r '.encoded_jit_config') && ~/actions-runner/run.sh --jitconfig $jitconfig

You already have access to most of these with the config options as they are currently. According to the docs, it also works with GitHub apps, so maybe it could even replace the current implementation (not confident on that).

I can try my hand at doing it myself, but wanted to get your opinion on its inclusion first.

Thanks again!