Erase faster to increase eraser size

[Mitia99]

Feature request
Erase faster to increase eraser size

https://github.com/flxzt/rnote/assets/56766778/687e4490-36c8-4254-9ed9-db253fafcbf7

Additional context
It's available on Microsoft Whiteboard

I find it pretty convenient and the gesture feels natural.

Thanks for considering this,

[PerfectlyInternal]

I'd be willing to take on this feature, it looks like nobody else has started on it.

[Doublonmousse]

@PerfectlyInternal See also https://github.com/flxzt/rnote/discussions/957

Not sure things have moved since then (I think it's free for you to take), but the help there should still be pretty much valid.