Return user to connected accounts when cancelling revocation

[aduth]

🛠 Summary of changes

Updates the connected accounts revocation screen to return a user to their connected accounts (where they came from) if they choose to cancel revocation, rather than the root accounts dashboard.

It also includes a handful of general code quality improvements:

• Use standard PageFooterComponent
• Update feature specs to interact with the page as a user would be expected to, rather than visiting URLs directly
• Avoid redundant navigation in feature specs
• Avoid redundant assertions (e.g. checking history path in revocation scenario, when already asserted in preceding scenario)

📜 Testing Plan

1. Go to http://localhost:3000
2. Sign in
3. From accounts dashboard, click "Your connected accounts"
4. Click "Disconnect" on one of your connected accounts
   a. If you don't have a connected account, run and sign in through sample application
5. When prompted to confirm revocation, click "Cancel"

Before: You'd be returned to the root account dashboard screen
After: You're returned to the "Your connected accounts" page (where you came from)