[CI] `sys` tests for nodejs

~~`sys` api tests are currently not run for nodejs (as this is not a sys target by default).~~
They now have been added.

These can be added for nodejs, however, there exist the following limitations:
- [x] `sys.io.File.update()` is not present in the hxnodejs api
- [x] `eof` checks work differently in hxnodejs compared to other targets
- [x] On unix, hxnodejs's `FileSystem.absolutePath("c:\filepath")` returns `"/path/to/cwd/c:\filepath"`, whereas on other Haxe targets it just returns `"c:\filepath"`
- [ ] `sys.io.Process` does not exist in hxnodejs
- [ ] `sys.net.Socket.bind()` is not implemented in hxnodejs
- [x] The test for `sys.io.File.append()` fails on Mac: #12573 and https://github.com/HaxeFoundation/hxnodejs/pull/197
- [ ] `haxe.Http.customRequest()` (synchronous http) is not implemented in hxnodejs

I created hxnodejs PRs to fix the first three:
- https://github.com/HaxeFoundation/hxnodejs/pull/180
- https://github.com/HaxeFoundation/hxnodejs/pull/181
- https://github.com/HaxeFoundation/hxnodejs/pull/182

For the rest, the tests can temporarily be removed for nodejs using conditional compilation, and they can be added back later when/if the APIs are updated.

See also: #10176