buttonrebinds: Allow binding mouse button actions and tablet tool buttons
These are done together because it seems to be a major use-case to bind tablet tool buttons to mouse buttons for many artists.
- Allow configuring tablet tool rebinds (what we have in 5.26 are tablet pad buttons)
- Allow binding mouse button and tablet tool button actions
- Ensure we don't enter binding loops
Edited by Aleix Pol Gonzalez