Reapply "VACMS-16853: next build branches ftw (#17154)" (#17261)

[alexfinnarn]

Description

closes #16853

Testing done

• Updated some tests for git information/API/frontend.
• Manually tested locally by running script.
• Tested on Tugboat

QA steps

1. Log in and go to "/admin/content/deploy/next"
   • Confirm you can select versions of next-build and vets-website from git references
   • Confirm there is no build in progress
   • No request or lock files should exist
   • The versions for next-build and vets-website should be "__default"
2. Submit the form with two branches chosen for next-build and vets-website
   • Confirm that a build request file exists.
   • No build should have started yet so no lock file should exist.
   • The versions for next-build and vets-website should be reported as what you selected.
3. Refresh the page a few times until the background process kicks off from reading the build request file.
   • Confirm that the form fields are locked during the build.
   • Confirm you can view the build log file and it is adding data until the build finishes.
4. Refresh the form page after the build is complete
   • Confirm the disabled fields are no longer disabled.
   • View the log to see that the build finished. It might have an error, but that will be addressed in future tickets.
5. Navigate to "/admin/content/deploy"
   • Confirm that the vets-website version is not the same as the one you chose on "/admin/content/deploy/next".

Definition of Done

• Documentation has been updated, if applicable.
• Tests have been added if necessary.
• Automated tests have passed.
• Code Quality Tests have passed.
• Acceptance Criteria in related issue are met.
• Manual Code Review Approved.
• If there are field changes, front end output has been thoroughly checked.

Select Team for PR review

• CMS Team
• Public websites
• Facilities
• User support
• Accelerated Publishing

[timcosgrove]

Just putting language changes in here.

[alexfinnarn]

reopen to kick Tugboat

[tjheffner]

One minor quibble about language in the readme, but QA steps check out, and a different version of vets-website is used for the existing content release form and the new content/deploy/next form.

Two things I notice --
The link to the last build log disappears once the build has completed, I think it would be worthwhile to display a link to the log file if it has been built prior, even if a build is not currently in progress.

Also we get new vets-website branch, but we don't actually use the assets from it because we aren't rebuilding/pulling. I don't think that's a blocker for this ticket, can be addressed as part of #17209.

Overall, great work.

Noting this cannot be merged until the next-build and vets-website-for-next-build repos are added as part of the BRD process, otherwise staging will break again.

[tjheffner]

we aren't building the static frontend here, we are re-building the preview server provided by next-build

[alexfinnarn]

I'm fine with whatever changes would best reflect what is happening when the form gets saved. I know @timcosgrove made updates to the language and I think I kept them all, but maybe I did not.

[alexfinnarn]

@tjheffner I added the "display a link to the log file if it has been built prior, even if a build is not currently in progress" note as an AC criterion to #17209. It shouldn't require much effort.

[alexfinnarn]

I am closing this for the time being so Tugboat has more resources, the last build failed anyway, and it can't be merged until https://github.com/department-of-veterans-affairs/devops/pull/14070 is merged.