LPS-45577 Validating different LAR types

Hey Brian,

We had an original fix, but after consulting w/ product management we have decided that what the fix is fixing should not be allowed at all, we should validate if someone wants to import a layout set prototype to a layou set. This should not be allowed at all.

Dániel rolled back the changes, and he wrote test for it, what I'm extended a bit.

Thanks,

Máté

cc: @epgarcia