After a serious breakage to keyboard navigation through the blocks reported in #11773 and solved #12390 during Release Candidate time, there is consensus an e2e test specific to check keyboard navigation through blocks would be valuable.

The bug report on #11773 followed the following workflow, maybe it could be used as a basis for the test:

• create 3 paragraphs blocks with some content
• navigating with the Tab key should navigate the 3 blocks UI as expected, in the expected order which at the moment is:
  • block external focusable wrapper
  • add block button
  • block movers
  • block toolbar
  • block editable area
• note: this order might change in the future so it would be great if the test could be easily adjusted
• move to another part of the Gutenberg UI, for example using the navigate regions shortcut or clicking elsewhere as reported in Tabbing skips the blocks UI in various workflows #11773
• repeat keyboard navigation through the 3 blocks to verify everything works as expected