fixrules(ARIA region landmark rules): Improve consistency of failure messages

[philljenkins]

Improve consistency of failure messages for the following ARIA "landmark region" related rules:

1. aria_application_label_unique
2. aria_application_labelled
3. aria_article_label_unique
4. aria_banner_label_unique
5. aria_banner_single
6. aria_banner_one
7. aria_content_in_landmark
8. aria_contentinfo_single
9. aria_complementary_label_unique
10. aria_contentinfo_label_unique
11. aria_contentinfo_label_visible
12. aria_document_label_unique
13. aria_form_label_unique
14. aria_main_label_unique
15. aria_main_label_visible
16. aria_main_labelled
17. aria_main_single
18. aria_navigation_label_unique
19. aria_region_label_unique
20. aria_region_labelled
21. aria_search_label_unique
22. aria_toolbar_label_unique

This PR is related to the following issue(s):

• Fixes ARIA landmark rule's messages consistency #1379
• see proposed changes in ARIA consistent messages.xlsx

Testing reference:

I have conducted the following for this PR:

• I validated this code in Chrome and FF
• I validated this fix in my local env
• I provided details for testing
• This PR has been reviewed and is ready for test
• I understand that the title of this PR will be used for the next release notes.

[philljenkins]

@tombrunet this PR is still looking odd, it now shows "merged" and no longer shows in the list of opened PR https://github.com/IBMa/equal-access/pulls. It also shows 232 changed files, of which none of these are part of the original scope of this PR and issue.

So I'm going to create a new branch and a new PR for the ARIA landmark work.