`Project Individual Elements` was never supported for `Vert Slide` and
`Edge Slide`, however, albeit erroneously, this option still affected
those operations.
In Blender 3.6 this situation of `Project Individual Elements`
affecting the result, has been "fixed". But users still preferred the
old behavior.
Therefore, instead of falling back to `Snap To Face`, support
`Project Individual Elements` for `Vert Slide` and `Edge Slide`.
This is more like how it worked previously.
