Migration plan to psygnal

[melonora]

📚 New content request

While we have talked about migrating the way we handle our events to psygnal many times, it is a big task for which a plan was never created. This makes it so we fall into the trap of decision paralysis. In order to alleviate this, the initial step will be to create a NAP with a migration plan, which should live as a document to be iterated on as the work is carried out.

Outline

NAP!

[jacopoabramo]

I played around in the past with that, in napari/napari#8387

The PR is very old so a lot of things might have changed, but maybe it could help give some context.

The PR is very messy because I tried to implement both fully typing coverage (unsuccessfully) and migrate to psygnal. That's because my understanding (which may be at fault) is that you can't have the latter without the former.

EDIT: I'm way late to the party, @melonora already mentions the PR in the NAP draft. Thanks!