URL scheme: Find or Create action

[gingerbeardman]

Describe your feature request From: https://github.com/glushchenko/fsnotes/issues/1296#issuecomment-1104267056

It would be good to create a new note by URL scheme only if it does not already exist.

Proposal I'm proposing that behaviour of "new" to be changed: it would open an existing matching note, or only if there are no matches create a new note.

Example Post text to the weekly note, calling with different txt would append to same note

fsnotes://new/?title=2023-w04&txt=%23%23%202023-01-26

Additional context Request from @jamesgecko