fix(region): allow role=dialog and svg elements outside regions

[straker]

I was looking into how our region rule was passing a test for role=dialog when an issue said it wasn't. Turns out our test wasn't written correctly so even though the code should have been failing it wasn't. I made sure to edit all the tests to ensure they work as expected and added a note at the top of the file on how to properly add a new test fixture.

I also removed the form with title test since with 4.0 it is no longer considered a landmark and also suffered from the same problem as the dialog test.

Lastly, our code already supported a regionMatcher option so I just made sure to provide defaults for dialog and svg.

Closes issue: #1832 and #2556

Reviewer checks

Required fields, to be filled out by PR reviewer(s)

• Follows the commit message policy, appropriate for next version
• Code is reviewed for security