Openpgp parser for keyrings

[lambdafu]

Tracking here the changes for a new OpenPGP parser.

[lambdafu]

Next steps:

• [x] Refactor PublicKeyPacket (because the versioned data can also be used in a secret key or a sub key packet), into PublicKeyPacket and PublicKeyData.
• [x] Add fingerprint and key id interfaces to PublicKeyData.
• [x] Add key ID output to "packet filter" subcommand.

[lambdafu]

Next steps:

• [x] Implement signature subpackets (ouch)
• [x] Implement public key and signature material for Ecdsa, Ecdh, and Eddsa
• [ ] Implement user attribute packets

[codecov[bot]]

Codecov Report

Merging #60 into master will increase coverage by 3.65%. The diff coverage is 79.27%.

@@            Coverage Diff             @@
##           master      #60      +/-   ##
==========================================
+ Coverage   16.87%   20.53%   +3.65%     
==========================================
  Files         183      294     +111     
  Lines       30790    32769    +1979     
==========================================
+ Hits         5197     6730    +1533     
- Misses      25593    26039     +446

[lambdafu]

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