Change `redundant_pattern_matching` to also lint `std::task::Poll`
`reduntant_pattern_matching` currently lints pattern matching on `Option` and `Result` where the `is_variant` utility methods could be used instead: `is_some`, `is_none`, `is_ok`, `is_err`. This PR extends this behaviour to `std::task::Poll`, suggesting the methods `is_pending` and `is_ready`.
Motivation: The current description of `redundant_pattern_matching` mentions
> It's more concise and clear to just use the proper utility function
which in my mind applies to `Poll` as well.
changelog: Enhance [`redundant_pattern_matching`] to also lint on `std::task::Poll`
f897d27d8b