Fix #7737: Crash at Browsing Mode Change while drag-drop action in Tab Tray

[soner-yuksel]

Adding check for active drag and drop while mode change

Summary of Changes

This pull request fixes #7737

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:

• Launch Brave
• Open at least 2 tabs
• Tap on Tab switch button
• Tap and hold on any tab, so you can drag the tab around
• Now keep holding/dragging the tab and with another finger tap Private button > Observe Brave is crashing

Screenshots:

RPReplay_Final1690299361.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).

[iccub]

👏