Feature request: Add in the signals-devtools-ui

Signals are a Preact project, let's add in the signals-devtools(-ui) so that we can have a new signals tab. There's prior art in https://github.com/preactjs/signals/tree/main/extension which can be re-purposed to make it work in the Preact devtools.

It would be really nice if this made it possible for Render reasons: state changed could specify which signals changed.