This PR is a refactor / tidy up of some snapping logic.
- Fix a bug where the recursive call to `findAdjacentGaps` could lead to
a maximum call stack error
- Fixed an issue that caused handle snapping to expensively recompute
- Fixed a dependency from the snap manager to the line shape
### Change Type
- [x] `patch`
### Test Plan
Our snap tests are pretty thorough, they should work here.
### Release Notes
- [editor] fix bug in snapping
b22bb13bb0