Implements first two points of #8745
1. The fix for drop-down was simple, just stop click propagation
2. The fix for connections was much more complicated. It turned out, that it's about keeping track of hovered ports; when picking an option in WidgetSelection makes the drop-down disappear - but that won't emit `pointerleave` event, so the port was still deemed hovered. Changed the mechanism for tracking hovered port to more "centralized" one.
- Closes#8072
- Implement handlers for the corresponding buttons on the circular menu
- Add missing icons and styles
- Add functionality to match and extract ASTs
# Important Notes
None
