[Editor] Eraser editor and eraser button to be able to erase annotations

[legraina]

I have created an eraser button to be able to erase annotations. The goal of this eraser is to remove parts of some annotations (which are erasable), especially the ink annotations. When you write, in particular on a tablet, you may want to erase parts of your writing, it’s where this eraser comes in play, like a real eraser/rubber. There is nothing added to the document it-self, as it just modifies current annotations. It replaces closed PR #20192.

• Eraser:
  • Create an eraser editor: eraser.js
  • Abstract erase and endErase functions in editor.js, as well as an erasable field (false by default)
  • Implemented erase and endErase for ink.js
  • Implement undo/redo logic for the eraser. endErase function return a dictionnary { cmd, undo } with the right functions to use for the eraser undo and cmd.
  • Add an eraser button