Change offsetX and offsetY calculations in PointerEventManager (#2938)

## Description

While working on `PointerTracker` refactor and adding `relativeCoords` to it, I've noticed that `offsetX`/`offsetY` in `PointerEventManager` use `PointerEvent.offsetX` (and `offsetY` respectively) while `TouchEventManager` calculates this property by calculating the difference between `clientX` and bounding box (`event.clientX - rect.left`). I've decided to unify this behavior so that `offset` is now calculated in `PointerEventManager` the same way as in `TouchEventManager`.

As. you can see in the videos below, those 2 values may have different results - that is the main reason behind unifying them. `offset` property is used only in `relativeCoords` which have been recently introduced, so it won't be a breaking change.

## Test plan

Tested by adding `console.table` in `onPointerMove` inside `PanGestureHandler`

Author: m-bert

src/web/tools/PointerEventManager.ts

@@ -238,13 +238,14 @@ export default class PointerEventManager extends EventManager<HTMLElement> {
   }
 
   protected mapEvent(event: PointerEvent, eventType: EventTypes): AdaptedEvent {
+    const rect = this.view.getBoundingClientRect();
     const { scaleX, scaleY } = calculateViewScale(this.view);
 
     return {
       x: event.clientX,
       y: event.clientY,
-      offsetX: event.offsetX / scaleX,
-      offsetY: event.offsetY / scaleY,
+      offsetX: (event.clientX - rect.left) / scaleX,
+      offsetY: (event.clientY - rect.top) / scaleY,
       pointerId: event.pointerId,
       eventType: eventType,
       pointerType: