Add pyqtProperty->Property and pyqtBoundSignal->SignalInstance

[tlambert03]

closes #274

didn't wait for your response... but just in case it was an oversight, this adds back some of the PyQt6 specific logic around signals and properties in QtCore.

[CAM-Gerlach]

Hey @tlambert03 , thanks for this. Sorry it wasn't clear from the title or the description, but it looks like all the changes here, save the QDateTime.toPyDateTime alias, are already made in PR #271 . As that is very nearly a superset of these changes, and this would need a fixup on your end or a squash on ours to fix the duplicate commits and add more appropriate commit messages, for simplicity's sake and to reduce merge conflicts, I'm thinking it might be best to add the QDateTime.toPython line to #271 (since its almost ready) assuming @dalthviz agrees, and give you a Co-authored-by: credit on the relevant commit there. How does that sound to you?

[tlambert03]

sounds good! no need to for the co-authored-by... it's just a copy and paste job from pyqt5 :)
sorry I missed the addition in #271!

[CAM-Gerlach]

No worries, thanks again for pointing this out!