[FR] Simple sketch tool for document workspace

### Description

Sketch tool such as [excalidraw](https://excalidraw.com/) implemented as a block for the document workspace. Logseq already has this feature (as /draw) and it's great for simple sketches.

There's already something like this that someone worked on https://github.com/JideGuru/flutter_drawing_board but I would recommend some tweaks:
- UI more like excalidraw.
- Additional features from excalidraw: line sloppiness (https://user-images.githubusercontent.com/5153846/101990286-644df380-3ca6-11eb-81c1-c95695d38a93.png), edge type (round, sharp), stroke type, shape alignment, background color, export as SVG, hand tool, shape selection, proportional shapes, resize and rotate shapes.
- Using eraser to break path between two points on a shape.
- Few more shapes like the spiral, triangle, etc.
- Adding points to existing shapes.
- Adding text.
- Allowing to go full screen.
- Default mode as a block should be view only, with no toolbars visible.

Edit: there's another package that's even more complete: https://github.com/Y0ngg4n/fluffy_board

### Impact

All users that need sketching

### Additional Context

I understand that this is a lot. I will try to see how it's implemented and add some features myself.