LG-12904 add axe tests

[Sgtpluck]

Relevant Ticket or Conversation:

https://cm-jira.usa.gov/browse/LG-12904

Description of Changes:

This change backfills a bunch of accessibility tests for views that were previously untested. The change includes:

• moving some authorization logic to the pundit Policy classes
• updating existing tests
• adding tests
• fixing accessibility and html validation errors

PR Checklist:

1. [ ] Have you linted and tested your code locally prior to submission?
2. [ ] Have you tagged the appropriate dev(s) for review?
3. [ ] Have you linked to any relevant tickets or conversations?

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