Use system cursors instead of embedded raster images where possible

[rubiefawn]

This PR changes several views to utilize the system's cursors where possible instead of setting the cursor to raster images.

Marking this as draft, since this currently only modifies uses of hand.png. There are other cursors that can also be updated in this same way.

[Rossmaxx]

While we are at it, would make sense to remove the hand.png file, and other cursor files as they are being removed.

[rubiefawn]

That is the intent yes

[AW1534]

On my system (KDE Wayland), there is no change. It still uses the wrong hand cursor
Scratch that, it works, but you forgot to change it for the clips (e.g sample clips, MIDI clips, B&B clips)

There are 2 mentions of the "hand" sprite in ClipView.cpp

[rubiefawn]

you forgot to change it for the clips

I didn't forget, this PR is marked as a draft for a reason. This PR is larger in scope than just hand.png, and the clips cursors are part of that scope.