Reject infix operators on command call on writes

[kddnewton]

Fixes #3106

[Earlopain]

This is casting too wide a net. This code used to be ok but now isn't:

# steep-1.10.0/lib/steep/interface/function.rb
kp = keyword_params | other.keyword_params or return
                                           ^~ unexpected 'or', expecting end-of-input
                                           ^~ unexpected 'or', ignoring it

I have a few more cases in https://gist.github.com/Earlopain/908f5744ae2c32bf4ab1d0a590b4e6c5 but I did not check them all. They all seem rather similar though (a = prefix != nil and prefix.length > 0, query_options = options.keys & [:select, :where, :order, :limit] and !query_options.empty?, etc.) so guessing it's the same cause for now.

Can you take a look?

[Earlopain]

I reverted for now in #3960 with some added tests for this