Support thoth image builds via github actions

[erikerlandson]

Is your feature request related to a problem? Please describe.
Developers on github are often familiar with using github actions, but are generally not familiar with more bespoke systems like thoth, aicoe-ci, etc.
cc @negillett @MichaelClifford @caldeirav @goern

User story:
As a maintainer of some github repo(s) that I would like built via thoth s2i, I am familiar with working with github actions, and I would like to be able to configure these builds to be managed via github actions, as an alternative to configuring a thoth yaml, installing thoth bots, and submitting specialized image-build issue forms. Having this managed via github actions allows me a single place to configure the building, and it allows me to control which gh events trigger the actions, which branches they are enabled, for, etc. It saves the log output of all builds via standard gh links which are persisted, so I (1) always know where to look for my build logs, and (2) I know these logs are saved.

High-level Goals

1. Implement a github action that can do thoth image builds.

Describe the solution you'd like
See above

References relating to customized github actions
Using custom images for actions
https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idcontainer
Hosting your own runner
https://docs.github.com/en/actions/hosting-your-own-runners

Describe alternatives you've considered
The alternative is to educate new community members on how thoth, sesheta, aicoe-ci, etc, work.
This is also a credible solution, but is more work than hypothetically saying "here use this github action..."

Acceptance Criteria

• Create a custom github action that can be used to do thoth builds

[Gkrumbach07]

Other benefits of having a GitHub action for Thoth image build:

• Less steps to integrate Thoth image builder. Instead if using yaml files and bots, a repo owner can simply add a preset GitHub action.
• An already integrated way to see past build logs and build fails. As a repo owner, you have better clarity of the history and current state of the image builds.
• External users are more likely to be familiar with the standards of a GitHub workflow file, giving them more flexibility to customize when the image build runs. i.e. GitHub workflow triggers.

[erikerlandson]

An already integrated way to see past build logs and build fails. As a repo owner, you have better clarity of the history and current state of the image builds.

this would also be an excellent solution for thoth-station/core#316

github's infra provides a standard link to the output of all its workflow steps, and they are also saved for future reference

[Gregory-Pereira]

/assign

[codificat]

/triage accepted
/priority important-soon
/sig user-experience

[sesheta]

Issues go stale after 90d of inactivity.
Mark the issue as fresh with /remove-lifecycle stale.
Stale issues rot after an additional 30d of inactivity and eventually close.

If this issue is safe to close now please do so with /close.

/lifecycle stale

[harshad16]

/remove-lifecycle stale