[#70420] Rework filter close buttons as IconButtons, fixing accessibility issues

[myabc]

Ticket

https://community.openproject.org/wp/70420 https://community.openproject.org/wp/70167

What are you trying to accomplish?

Fixes accessibility issues detected by both ERBLint and eslint relating to close buttons on the following parts of the UI:

• filter components
• Types > Form Configuration page group headers

Also adjusts (harmonizes) the positioning of the filter close button.

Screenshots

What approach did you choose and why?

These improvements have been extracted from the following Pull Requests (which are otherwise still WIP):

• #21503
• #21339

Introduces Angular octicon directive (dynamic icon component) that allows rendering an icon by name

Merge checklist

• [ ] Added/updated tests
• [ ] Added/updated documentation in Lookbook (patterns, previews, etc)
• [ ] Tested major browsers (Chrome, Firefox, Edge, ...)

[HDinger]

The test seems to be failing correctly. The rest looks fine 👍

[Copilot]

@myabc I've opened a new pull request, #21635, to work on those changes. Once the pull request is ready, I'll request review from you.