Generic key addition

[ptoffy]

This is a breaking changes which renames the addES256, addRS384 etc. methods to more generic ones such as addECDSA and addRSA

[0xTim]

Much prefer this API - looks good! Some comments/queries

[codecov]

Codecov Report

Attention: Patch coverage is 75.00000% with 14 lines in your changes are missing coverage. Please review.

Project coverage is 77.57%. Comparing base (c4828b0) to head (a40b25b).
Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #160      +/-   ##
==========================================
+ Coverage   73.56%   77.57%   +4.01%     
==========================================
  Files          59       59              
  Lines        1615     1400     -215     
==========================================
- Hits         1188     1086     -102     
+ Misses        427      314     -113     

Files	Coverage Δ
Sources/JWTKit/ECDSA/ECDSA.swift	85.71% <ø> (-0.29%)	⬇️
Sources/JWTKit/ECDSA/ECDSASigner.swift	90.90% <100.00%> (ø)
Sources/JWTKit/ECDSA/JWTKeyCollection+ECDSA.swift	100.00% <100.00%> (ø)
Sources/JWTKit/ECDSA/P256+CurveType.swift	100.00% <ø> (ø)
Sources/JWTKit/ECDSA/P384+CurveType.swift	100.00% <ø> (ø)
Sources/JWTKit/ECDSA/P521+CurveType.swift	100.00% <ø> (ø)
Sources/JWTKit/Utilities/CryptoSigner.swift	100.00% <100.00%> (ø)
Sources/JWTKit/X5C/X5CVerifier.swift	83.33% <100.00%> (-1.48%)	⬇️
Sources/JWTKit/HMAC/JWTKeyCollection+HMAC.swift	91.66% <90.47%> (+58.33%)	⬆️
Sources/JWTKit/JWTError.swift	44.06% <25.00%> (+20.48%)	⬆️
... and 2 more

... and 22 files with indirect coverage changes