21877 [ios] Refactor IOSSurface factory and unify surface creation (cla: yes, platform-ios)

21882 Revert “Add flag to not publish the observatory port over mDNS” (cla: yes, platform-ios)

21883 Add flag to not publish the observatory port over mDNS (cla: yes, platform-ios)

21890 Refactored the FlutterEngine to make it easier to implement spawn functionality (cla: yes, platform-ios)

21970 Revert “[ios] Refactor IOSSurface factory and unify surface creation” (cla: yes, platform-ios, waiting for tree to go green)

21975 Fixes Edge trigger route change announcement (cla: yes, platform-android, platform-ios, waiting for tree to go green)