Fix #8228: Use specific Scene resign functions when dealing with UI only

[Brandon-T]

Summary of Changes

• Do not ever use applicationWillResignActive for SCENE specific stuff.

• applicationWillResignActive is called for EVERY SCENE, but sceneWillResignActive is called only for the one scene that will resignActive.

• To fix the issue, we must only update UI for the one scene inside of the scene specific delegate. If updating UI for all scenes (or doing logic that applies to all windows), then we can do it inside applicationWillResignActive.

This pull request fixes #8228

Submitter Checklist:

• Unit Tests are updated to cover new or changed functionality
• User-facing strings use NSLocalizableString()
• New or updated UI has been tested across:
  • Light & dark mode
  • Different size classes (iPhone, landscape, iPad)
  • Different dynamic type sizes

Reviewer Checklist:

• Issues include necessary QA labels:
  • QA/(Yes|No)
  • 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 and pull request is assigned to a milestone (should happen at merge time).