Improve block inserter accessibility

[jd-alexander]

Fixes #915
Improves accessibility of the Inserter.

To test:
See WordPress/gutenberg#25549
PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered if this change warrants user-facing release notes more info and have added them to RELEASE-NOTES.txt if necessary.

[peril-wordpress-mobile]

Wanna run full suite of Android and iOS UI tests? Click here and 'Approve' CI job!

[etoledom]

Hey @jd-alexander !

It seems this branch needs to be updated with develop. I experienced an issue fixed by this PR: #2662

This is probably why CI is failing too.

Please let me know when it's ready! 🙏

[etoledom]

Hey @jd-alexander - I was talking a look to these CI errors. The failure from the. PR changes have definitely be fixed already 🎉

What I noticed is that the gutenberg side branch doesn't seem to be updated yet.
I'd recommend you to rebase that branch from origin/master (there seems to be a conflict there even, I tried locally). And then update once again the reference on this PR.

Having an updated gutenberg-mobile and an outdated gutenberg branch sounds like might arise problems.

This is what the Android UI Test look like on CI (not very helpful to me though):

[jd-alexander]

Thanks much for your help @etoledom I will definitely follow these steps from now to ensure everything is in sync 🙏

[etoledom]

Approved via WordPress/gutenberg#25549 (review)