Improve crypto provider API documentation

[ctz]

Some misc docs clean ups, but mainly trying to improve matters around CryptoProvider

[djc]

Nice!

[ctz]

Thinking about Jsha's feedback from #1603, should we also mention what the crate has typically provided to help guide what a provider should offer in a minimal support set to avoid confusion?

For whatever reason I can't reply to this in-thread.

I'm not sure. I think I probably want to avoid prescribing some mandatory-to-implement key types / parameters here, and just concentrate on making the link 100% crystal clear and leave people to it.

If we were to write some MTI suggestions, I guess most people would put RSA in there, and probably ECDSA. But I think that disavows a completely reasonable CryptoProvider which deliberately don't have or want to support those.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (b8b1327) 95.90% compared to head (fd2d01f) 95.77%.
Report is 15 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1608      +/-   ##
==========================================
- Coverage   95.90%   95.77%   -0.14%     
==========================================
  Files          77       79       +2     
  Lines       15742    16312     +570     
==========================================
+ Hits        15098    15623     +525     
- Misses        644      689      +45     

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[cpu]

If we were to write some MTI suggestions, I guess most people would put RSA in there, and probably ECDSA. But I think that disavows a completely reasonable CryptoProvider which deliberately don't have or want to support those.

That seems like a reasonable justification to avoid it 👍