ci(trigger): separate pr_build from build

[piyoki]

Background

As part of the roadmap mentioned in #156, this PR includes proposed changes to separate pr-based events from the build workflow. As a result, the ONLY difference is the trigger. In order to move forward to achieving CI modularity, this PR is necessary.

Checklist

• The Pull Request has been fully tested
• There's an entry in the CHANGELOG
• There is a user-facing docs PR against https://github.com/daeuniverse/dae

Full changelogs

• docs(README): add build status badge
• ci(trigger): separate pr_build from build
• ci: add run_name followed by #pr_number - pr_title @pr_ref:pr_sha
• ci: add initial job to show pr context
• ci: run build job after context job

Issue reference

As part of #156

Test Result

Ref: https://github.com/daeuniverse/dae/actions/runs/5494674099

[piyoki]

Ready for review.

[mzz2017]

LGTM~

[dae-prow]

🧪 Since the PR has been fully tested, please consider merging it.