[players] Fix persisted eraser path for annotations

[ivancea]

Problem

While erasing annotations, apparently erased lines will reappear later, because the code that stores the eraser mask uses a "limited" Fabric intersection calculation:

Fabric's intersectsWithObject() just checks the path bbox (Through getCoords()).

Unfortunately, that doesn't take the stroke width into account. In fact, not even intersectPolygonPolygon() accepts a stroke right now.

Note that live preview uses a different logic compared to the persisted mask.

Solution

Use a custom bbox check adding the radius. Until Fabric fixes it, that's a simple approach, and it keeps the performance of the original.