Fix #7855: Add 'Private tabs' settings section

[soner-yuksel]

Summary of Changes

This PR also organize and arrange the views and controller to desired folders for settings.

This pull request fixes #7855

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

Test Plan:

• Verify Private tabs under Tab section
• Verify Private tabs include Persistent Private Tabs toggle and Local Authentication Toggle
• Verify toggles are working as intended

QA: Search for Private Tab Mode Local Authentication Cases for additional information about cases

Screenshots:

RPReplay_Final1692029428.MP4

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).