Sculpting faceless meshes is not supported and since a lot of operators
/ API functions are accessing face sets, this would also lead to crashes
(this was reported for the color filter, but was also true for the cloth
and mesh filter for example).

This is an alternative to D10851 [which was a more localized solution
only preventing the crash in relation to face sets]. But after talking
to @Pablo Dobarro (pablodp606), it was suggested to prevent sculpt mode in a much more
general scope, and do so for face(or vertex-)less meshes.

So now prevent sculptmode via operator poll, but also cover a couple of
more cases (e.g. loading a file with a mesh like this in sculptmode).

Dont see a specific check like this for other mode-switching cases, so
unsure if this the way to go, not replacing D10851, but putting this up
as an alternative.

Fixes T86940: sculpt automasking facesets option crashes on meshes
without faces