Misc oscp pyo3 migrations

[facutuesca]

Part of #10676

This contains misc migrations for the ocsp files and pkcs7. One of the changes triggers a pretty big cargo fmt change in pkcs7.rs making the diff very difficult to read, so I split that change into a second commit.
The only thing that actually changes in the second commit is:

// pkcs7.rs:165
// before
let digest = asn1::write_single(&x509::ocsp::hash_data(py, py_hash_alg, &data_with_header)?)?;

// after
let digest = asn1::write_single(&x509::ocsp::hash_data(py, &py_hash_alg.as_borrowed(), &data_with_header)?)?;

the rest is all formatting.

I suggest reviewing the first commit normally, and then the second to check the above change.

cc @alex @reaperhulk

[facutuesca]

Ah this also removes the last of the ocsp_resp.rs warnings