Accessibility improvements for links and buttons

[nathandyer]

Status

Ready for review

Description of Changes

Fixes #6404

Changes proposed in this pull request:

• This PR adds and expands labels to improve accessibility in areas where existing descriptions were either missing, or lacking context for visually impaired users to be able to understand where they are in the system and where they will be navigating next.
• ~This PR also includes updated translation files, as new translations will be needed.~

Testing

How should the reviewer test this PR?

• Build the dev environment using the usual steps, then verify everything is working as expected.
• Optionally, enable a screen reader to verify these changes and see (or rather, hear) the differences first-hand.

Deployment

Any special considerations for deployment? Consider both:

1. Upgrading existing production instances.
2. New installs.

This will require new translations.

Checklist

If you made changes to the server application code:

• [x] Linting (make lint) and tests (make test) pass in the development container* * There are three failures with make test, but it appears to be unrelated to changes in this branch, and I still see those when I run make test for the develop branch as well. 653 tests pass.

Choose one of the following:

• [ ] I have opened a PR in the docs repo for these changes, or will do so later
• [ ] I would appreciate help with the documentation
• [x] These changes do not require documentation

[nathandyer]

@cfm Thanks for the thorough review! I especially appreciate the explanation about when to run make translate - I'm in the habit of regenerating translation files after any string changes in other projects, so I carried that over here. Your explanation makes sense, and I'll hold off on doing those manually from now on (so that it can be done once at the time of the localization freeze).

I believe I've made the requested changes, and have rebased to remove the previous changes to the translation files. Please let me know if there's anything else I need to do before this is ready to merge. Thanks!

[cfm]

@nathandyer, if you happen to get around to these changes tomorrow, I can review this again. Otherwise I'll stay tuned in the new year. :-)

[nathandyer]

@cfm I believe the one-liner commit I added should address the needs in _source_row.html. If I need to make any changes there, just let me know (I made some assumptions about ngettext, but I believe they're reasonable assumptions).

As we briefly discussed in a separate thread, the improvements you mentioned for col.html are worthwhile, but given the slightly different scope, I think it would make sense to do so outside of this PR. If you'd like to do so here, though, we certainly can.

[cfm]

Let's call this very belated spring cleaning....