NB: in order to produce correct IR origins, the source element kinds for
some FIR elements has been changed. As a side effect, mapping PSI to FIR
slightly changed: namely, for `a[b]++`, `a[b]` used to be mapped on
`set` call or callable reference, but now it is mapped on `get` call.
^KT-61891: Fixed
^KT-64387: Fixed
k1 would suggest `get` as well
but with current fir structure with fake desugaring
get is moved to the separate fake psi which doesn't exist
thus the problem is ignored for now
^ KTIJ-24025