Add pq native recipient and identity

[str4d]

Currently blocked on RustCrypto/KEMs#369.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 19 lines in your changes missing coverage. Please review.
✅ Project coverage is 57.06%. Comparing base (b5b68c4) to head (3539647).

Files with missing lines	Patch %	Lines
age/src/identity.rs	58.62%	12 Missing ⚠️
age/src/native/pq.rs	95.83%	3 Missing ⚠️
rage/src/bin/rage-keygen/main.rs	72.72%	3 Missing ⚠️
age/src/cli_common/recipients.rs	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #632      +/-   ##
==========================================
+ Coverage   56.40%   57.06%   +0.65%     
==========================================
  Files          45       46       +1     
  Lines        4480     4565      +85     
==========================================
+ Hits         2527     2605      +78     
- Misses       1953     1960       +7     

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[fgsch]

Thank you! I've just started using this branch in my project and it's been working great.

I noticed rage-keygen still generates X25519 keys. Should it switch to PQ by default or have an option to generate PQ keys?

[str4d]

Yes, I will be switching the default to PQ in this PR. I have most of the associated changes for that locally; the main thing I'm blocking on for that is the design of the flags (age-keygen went with a -pq flag but that was when it wasn't the default).