`os.chmod` is missing validation for `dir_fd` and `follow_symlinks` when `path` is a file descriptor

Bug report

Bug description:

The documentation for os.chmod says it is not correct to use dir_fd or follow_symlinks when path is an open file descriptor...

https://github.com/python/cpython/blob/f74cdf80a120649e4c353430da8cbd1305c00993/Modules/posixmodule.c#L4092-L4095

... but os_chmod_impl never checks it.

When path->is_fd is true it takes the fchmod path and returns success, so both keywords are ignored altogether:

https://github.com/python/cpython/blob/f74cdf80a120649e4c353430da8cbd1305c00993/Modules/posixmodule.c#L4146-L4149

Other os utils (I checked os.stat, os.chown, and os.utime) reject this combination with dir_fd_and_fd_invalid / fd_and_follow_symlinks_invalid before the syscall. os.chown for example:

https://github.com/python/cpython/blob/f74cdf80a120649e4c353430da8cbd1305c00993/Modules/posixmodule.c#L4548-L4550

(The Windows path also has the same problem with: path->is_fd going directly to win32_fchmod.)

CPython versions tested on:

CPython main branch

Operating systems tested on:

macOS

Linked PRs

• gh-156265

Comece em Modules/posixmodule.c, em os_chmod_impl, e inspecione os ramos path->is_fd para POSIX e Windows. Compare o tratamento deles com a validação usada por os.chown, os.stat e os.utime. A tarefa estará concluída quando combinações inválidas de dir_fd e follow_symlinks forem rejeitadas quando path for um descritor de arquivo, e o comportamento estiver coberto pelos testes os relevantes.