Geometry updates via signals

As discussed with @schmidtp, maybe we should switch to sending signals for new geometries instead of having subscribers monitor full geometry device (which, I believe, happens even when you just monitor a single property).

What I've just tested a bit:

1. updating geometry on geometry device, receiving it on assemblers
2. geometry device already up, bring up pipeline (manager asks geometry device to send signal after assemblers are up)
3. subscribers already up, instantiate geometry device

Issue with 3.: apparently, the [signal].connected is not populated when onInitialization is called. You'll note I for now added a await sleep(1) which seems sufficient - should we bother Karabo people about what the correct way is or does someone in calibration have more signal experience?