Activation at startup discussion

[Carreau]

From today's discussion,

we likely want a activate at startup event, except if a plugin requests that instead of enabling it by default, we should on next start ask "this plugin want to activate on startup, this can have consequences on the speed of napari stability and startup, to allow them to do so, go to preferences > plugins > allow blahblah blah".

We could also have a blessed list hardcoded but let's see later for how to do that.
Either PR against napari, or crypto key ?

[nclack]

Here's the notes from the discussion

I really like the opt-in on startup.

I would love to gracefully handle a situation where:

1. A user enables 50 plugins at startup
2. One or more of them crashes/hangs during activate

A bulk reset, some ability to remember which one(s) caused issues, etc. would be nice.