Fix pretty printing remote name in pp_expr function

[Premwoik]

This PR addresses #42 and adds missing pp for a remote name that is used by the call_intersect error formatter.

I also added a test case that confronts pp_expr with the sent example from the issue. The produced result is not fully correct and it needs further investigation.

I don't know why one fmt test won't work on CI when works locally:

code: res = ElixirFmt.format_error(error, [])
     stacktrace:
       :erlang.++("(non_error_kind(), payload, stacktrace() -> payload)", [])
       (gradualizer 0.0.0+build.1009.ref650998d) /home/runner/work/gradient/gradient/deps/gradualizer/src/gradualizer_fmt.erl:505: :gradualizer_fmt.pp_intersection_type/2

[erszcz]

I don't know why one fmt test won't work on CI when works locally

Hmm, interesting, I'll take a closer look at it, but will leave the PR open in the meantime.

[erszcz]

@Premwoik I see the CI passes now. Is there anything else left to do in this PR?

[Premwoik]

@Premwoik I see the CI passes now. Is there anything else left to do in this PR?

I think that the main goal is completed, and we can merge.