This commit exposes snap options in transform operators. These options
are needed for Python tools to control snapping without requiring the
tool settings to be adjusted.
The newly exposed options are:
- `snap_elements` for choosing which element(s) of target the source
geometry should snap to (ex: Face Raycast).
- `use_snap_self`, `use_snap_edit`, `use_snap_nonedit`,
`use_snap_selectable_only` for controlling target selection.
- `use_snap_project` for controlling Face Raycast snapping.
- `use_snap_to_same_target` and `snap_face_nearest_steps` for
controlling Face Nearest snapping.
Reviewed by: Campbell Barton (campbellbarton)
Differential Revision: https://developer.blender.org/D15398
c484599687