compiler: Transform M#{} to is_map(M)

Core should not understand M#{}

Instead transform M#{} to

    case _cor0 of
      <_cor1>
          when call 'erlang':'is_map'
                (_cor0) ->
          _cor1
      ( <_cor2> when 'true' ->
            primop 'match_fail'
                ('badarg')
        -| ['compiler_generated'] )
    end