Accessibility-insights-web: Landmark best practice rules should not be flagged as failures

[ferBonnin]

Describe the bug

This four rules should be best practice and not flagged in automated checks

• unique-landmark
• landmark-complementary-is-top-level
• landmark-banner-is-top-level
• landmark-contentinfo-is-top-level
• landmark-main-is-top-level
• landmark-no-duplicate-banner
• landmark-no-duplicate-contentinfo

To Reproduce
Steps to reproduce the behavior:

1. run automated checks in this page: https://webaim.org/intro/
   unique-landmark rule is marked as failed

Expected behavior

unique-landmark rule does not fail

Extension (please complete the following information)

• OS: Windows
• Version 2.0.5
• Chrome Version 72.0.3626.121
• Target Page https://webaim.org/intro/

Are you willing to submit a PR?

No

If asked, will you be willing to submit a PR to fix this bug?
No

Did you search for similar existing issues?

Yes

Did you search for similar issues in our github issues or on stackoverflow
Yes

Additional context

Reported in Twitter: https://twitter.com/jared_w_smith/status/1107791754206441472

[dbjorge]

The fix to omit the rules as best practices is straightforward (add BestPractice to the corresponding link configurations in rule-to-link-mappings.ts), but doing so revealed an issue where old assessments in progress with state for rules that were removed cause DetailsView to crash on load, so that will need to also be resolved as part of this fix.

[dbjorge]

There are two more affected rules to fix, so re-opening/editting description

• landmark-no-duplicate-banner
• landmark-no-duplicate-contentinfo