add "Sketches" folder

[aster94]

I promise that this is my last issue

in the arduino IDE there is a very useful "Sketches" folder where the users put its project, code snippets, recipes, etc

it can be set from the IDE preferences

and, it could be obtained from the arduino's preferences.txt file
excactly from this line: sketchbook.path=

note that this is exaclty the same path of the user's library folder

I think that adding this Sketches folder at this place in vscode would be very useful for the user who are used to have their sketches easily accesible

[czgtest]

@aster94 Thank you a lot for your feedback, it is a nice feature request.

[aster94]

solved with #654

[czgtest]

This feature is already online on v0.2.23