refactor: Migrate to PointerEvents (#6598)

* refactor: Remove checks for PointerEvent support.

* refactor: Deprecate and remove calls to splitEventByTouches.

* refactor: Deprecate and remove calls to setClientFromTouch().

* refactor: Use PointerEvent in place of Event/MouseEvent/TouchEvent/PseudoEvent.

* refactor: Update references to mouse/touch events in code and documentation to reference pointer events.

* refactor: Merge Gesture and TouchGesture

* chore: clang-format changed files

* refactor: Bind and expect PointerEvents instead of MouseEvents.

* refactor: Rename TouchGesture to Gesture.

* fix: Fix test failures.

* chore: clang-format changed files.

* fix: Fix errant _ from merging

* refactor: Clean up dead code in browser_events.ts.

* chore: Update version in deprecation notices to reflect release schedule

* fix: Fixed a bug that caused the browser context menu to not be suppressed in Chrome.

* fix: Re-export Gesture as TouchGesture for backwards compatibility.

* refactor: Deprecate and remove uses of opt_noPreventDefault.

* chore: Fix error message in gesture.ts.

* chore: Removed obsolete todo.

scripts/migration/renamings.json5

@@ -1424,5 +1424,9 @@
 
   'develop': [
     // New renamings go here!
+    {
+      oldName: 'Blockly.TouchGesture',
+      newName: 'Blockly.Gesture',
+    },    
   ]
 }