tests: OTP-27 compatible

Summary:
- The type `file:fd()` has changed between OTP 26 and OTP 27 - erlang/otp@218ecbe#diff-7f2ad64a34b87080776f94ed42c8f0de5232c9e0d2db74c8e5e48fa2bf4963cb, which now results into different error messages on different OTP versions
- massaging the tests to not use the type `file:fd()` directly, - this relies a bit on how much eqwalizer unfolds when reporting a subtype error, but this is the best we can do right now to preserve the tests and to run them the same way both on OTP 26 and OTP 27

Reviewed By: michalmuskala

Differential Revision: D59757111

fbshipit-source-id: 70ac1be599ee21e824618833ab883c7f25563bf0

Author: ilya-klyuchnikov

crates/elp/src/resources/test/eqwalizer_tests/check/custom.pretty

@@ -2214,14 +2214,12 @@ error: incompatible_types
      │     │
      │     Device.
 Expression has type:   file:io_device()
-Context expected type: file:fd()
+Context expected type: #file_descriptor{}
 
 See https://fb.me/eqwalizer_errors#incompatible_types
      │     
 
-  file:io_device() is not compatible with file:fd()
-  because
-  pid() | file:fd() is not compatible with file:fd()
+  file:io_device() is not compatible with #file_descriptor{}
   because
   pid() | file:fd() is not compatible with #file_descriptor{}
   because
@@ -2235,14 +2233,12 @@ error: incompatible_types
      │     │
      │     Device.
 Expression has type:   file:io_device()
-Context expected type: file:fd()
+Context expected type: #file_descriptor{}
 
 See https://fb.me/eqwalizer_errors#incompatible_types
      │     
 
-  file:io_device() is not compatible with file:fd()
-  because
-  pid() | file:fd() is not compatible with file:fd()
+  file:io_device() is not compatible with #file_descriptor{}
   because
   pid() | file:fd() is not compatible with #file_descriptor{}
   because

test_projects/eqwalizer_tests/check/src/custom.erl

@@ -7,7 +7,7 @@
 
 -import(maps, [get/2, get/3]).
 -compile([export_all, nowarn_export_all]).
-
+-include_lib("kernel/include/file.hrl").
 -record(foo, {
     a :: ok | error,
     b :: number(),
@@ -2158,21 +2158,21 @@ file_open1() ->
         file:open("/file", [read]),
     Device.
 
--spec file_open2() -> file:fd().
+-spec file_open2() -> #file_descriptor{}.
 file_open2() ->
     {ok, Device} =
         file:open("/file", [read, raw]),
     Device.
 
 -spec file_open3_neg
-    ([file:mode()]) -> file:fd().
+    ([file:mode()]) -> #file_descriptor{}.
 file_open3_neg(Modes) ->
     {ok, Device} =
         file:open("/file", Modes),
     Device.
 
 -spec file_open5_neg
-    (file:mode()) -> file:fd().
+    (file:mode()) -> #file_descriptor{}.
 file_open5_neg(Mode) ->
     {ok, Device} =
         file:open("/file", [Mode]),