Fix #1707: Configure popover on iPad for restoring excluded publishers

[kylehickinson]

Summary of Changes

This pull request fixes issue #1707

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()

Test Plan:

• Enable rewards, create a wallet
• Stay on a site long enough for and navigate away to add it to the AC table
• Open AC table (rewards settings > AC details). Swipe to exclude the entry
• Tap restore 1 excluded site and verify that it doesn't crash

Screenshots:

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • release-notes/(include|exclude)
  • bug / enhancement
• Necessary security reviews have taken place.
• Adequate unit test coverage exists to prevent regressions.
• Adequate test plan exists for QA to validate (if applicable).
• Issue is assigned to a milestone (should happen at merge time).

[kylehickinson]

Possible other solutions:

• Overriding the trait collection on the panel to force it to be compact-width. This would then display the alert as usual as an action sheet
• On iPad, removing the prompt
• On both, removing the prompt