Rollup merge of #5848 - Ryan1729:add-derive_ord_xor_partial_ord-lint, r=matthiaskrgr

Add derive_ord_xor_partial_ord lint

Fix #1621

Some remarks:
This PR follows the example of the analogous derive_hash_xor_partial_eq lint where possible.
I initially tried using the `match_path` function to identify `Ord` implementation like the derive_hash_xor_partial_eq lint currently does, for `Hash` implementations but that didn't work.

Specifically, the structs at the top level were getting paths that matched `&["$crate", "cmp", "Ord"]` instead of `&["std", "cmp", "Ord"]`. While trying to figure out what to do instead I saw the comment at the top of [clippy_lints/src/utils/paths.rs](https://github.com/rust-lang/rust-clippy/blob/f5d429cd762423901f946abd800dc2cd91366ccf/clippy_lints/src/utils/paths.rs#L5) that mentioned [this issue](https://github.com/rust-lang/rust-clippy/issues/5393) and suggested to use diagnostic items instead of hardcoded paths whenever possible. I looked for a way to identify `Ord` implementations with diagnostic items, but (possibly because this was the first time I had heard of diagnostic items,) I was unable to find one.

Eventually I tried using `get_trait_def_id` and comparing `DefId` values directly and that seems to work as expected. Maybe there's a better approach however?

changelog: new lint: derive_ord_xor_partial_ord

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