Implement AF canonical page

[JonellaCulmer]

What we're after: Using the design created below and data moved to the API in 7.2, we want to begin to implement the front-end canonical pages for AF pages.

We're basing this first iteration on the MUR pages currently implemented in production.

Updated mockup following conversations during design sync and dev pairing.

Completion criteria:

• Make the AF canonical page.
• Send to AF for review.
• Add feature flag for AF canonical page.

[patphongs]

Noting these changes that were discussed and implemented:

• Removed petition decision columns in table.
• Add disposition field to summary section
• Left nav should have only Summary and Documents sections
• Ignore "Open case document" button and date
• AF canonical page mappings were mapped according to this spreadsheet 🔒