Revamp painting page

This replace Washipad components with QML Canvas. While Washipad is a great project, for this usecase the QML canvas is easier to use, more flexible and requires less maintenance.
The UI was also tweaked to be nicer on the eyes and easier to use, credit where credit is due, heavy inspiration on Marknote for that part.

On top of that this adds features and solves some issue:

• The auto crop is now more reliable
• The canvas is now transparent by default
• The color bar has a nicer UI
• Tools have been moved to a floating sidebar
• Possibility to choose the stroke size
• Possibility to draw a Rectangle
• Possibility to draw a Circle
• Possibility to draw Text, in bold or italic.

All the new shape can be outlined, filled, or both.

Preview:

P.S: I'm a very good artist, I know 😆