Support querying peer reputation (#2392)

# Description

Trivial change that resolves
https://github.com/paritytech/polkadot-sdk/issues/2185.

Since there was a mix of `who` and `peer_id` argument names nearby I
changed them all to `peer_id`.

# Checklist

- [x] My PR includes a detailed description as outlined in the
"Description" section above
- [x] My PR follows the [labeling requirements](CONTRIBUTING.md#Process)
of this project (at minimum one label for `T`
  required)
- [x] I have made corresponding changes to the documentation (if
applicable)
- [ ] I have added tests that prove my fix is effective or that my
feature works (if applicable)

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Co-authored-by: Bastian Köcher <[email protected]>