Blender Git Loki

Object: Enable transfer mode functionality for switching objects in Sculpt Mode

This implements the changes discussed in T87134 for including switch
object funcionality in 2.93. This includes:

- Remove the switch object operator experimental option
- Remove the option for switching objects in Edit Mode.
- Rename switch_object to transfer_mode.
- Enable the operator only in sculpt mode.
- Expose the operator in the Sculpt menu with an eyedropper modal
option.

On later releases, we could revisit enabling the operator in other mode
and object types as well as its place in the UI.

Reviewed By: JulienKaspar, JacquesLucke

Differential Revision: https://developer.blender.org/D10953