perf(aria/grid): avoid excessive change detections

[crisbeto]

Fixes that the grid was running change detection on pointermove events even when the user isn't dragging to select cells.

Fixes #32700.

[AdrianRomanski]

@crisbeto cool staff! I was reading the issue yesterday and trying to solve it in my head and your solution did not pop up :D
but now when im looking on it it makes 100% sense to fix it like that!
Noice

    // Since `pointermove` fires on each pixel, we need to
    // be careful not to hit the zone unless it's necessary.
    ngZone.runOutsideAngular(() => {
      this.element.addEventListener(
        'pointermove',
        event => {
          if (this._pattern.acceptsPointerMove()) {
            ngZone.run(() => this._pattern.onPointermove(event));
          }
        },
        {passive: true},
      );
    });

[crisbeto]

This PR was merged into the repository. The changes were merged into the following branches:

• main: 0395ca2
• 21.1.x: 81b407d