feat(ui): add cancel and clear all as toggleable app feature

[psychedelicious]

Summary

Add Cancel and Clear All as an AppFeature, allowing it to be disabled.

When disabled, if we need to render something in its place, the Cancel All Except Current button is rendered instead.

Related Issues / Discussions

Offline discussion

QA Instructions

The Cancel and Clear All button is rendered in 4 places. Here are what those places look like when that feature is disabled.

• The main cancel button - replaced by Cancel All Except Current:
  
• The queue actions menu - omitted in the list:
  
• The floating panel buttons - replaced by Cancel All Except Current:
  
• The queue tab controls - replaced by Cancel All Except Current:
  

Merge Plan

n/a

Checklist

• The PR has a short but descriptive title, suitable for a changelog
• Tests added / updated (if applicable)
• Documentation added / updated (if applicable)
• Updated What's New copy (if doing a release after this PR)