Add repo publishing

[jinnatar]

This one, when finalized, will make it either go live or boom.

Related: kanidm/kanidm#3078

TODO:

• Try out the deploy key warcrime: Would need to build on a different action, or see if FR: Using a deploy key instead of OAuth token crazy-max/ghaction-github-pages#230 goes anywhere.
• Test everything
• Rewrite this TODO into an actual deployment plan
• Flip all the TODO values to real ones
• Get the parent PR finalized
• Yeet this into main.
• If successful, come back and enable import & extend in the aptly action.

[yaleman]

You could move this down to the "publish to PPA" step so it runs all the other bits regardless.

[yaleman]

minor nit but otherwise 🥳

[yaleman]

DEPLOY_PAT has been added

[jinnatar]

Latest run seems to be as expected: https://github.com/kanidm/kanidm_ppa_automation/actions/runs/11318699131?pr=4
.. i.e. builds succeed now for nightly, but fail for stable. I've created an example backport PR at kanidm/kanidm#3108 which should make stable buildable without affecting the v1.3.3 tag.

But I could also just rip out the stable category now and launch with only nightly? I don't think it would kill the upgrade path for anyone.

[jinnatar]

Run is looking good so lets see what happens!