add shortcut to insert current date

[feiss]

A little proposal, that could make some people's lives a bit easier :)

Many times on my notes I find it useful to insert today's date, to have more info and context about the block. Specially when noting down things related to meetings, decisions made, etc.

This inserts the current date into the cursor's position, using F5. It's a very naive and simple first approach. Date format is very simple and could be customized by the user, and the shortcut is just the first thing I came up with, it could be anything else.

Sorry VSCode passed a linter on these files and the PR seems bulkier than needed. Can revert those if you want