Add support for saving quic tokens.

[bwelling]

This caches tokens in the manager, so that they can be used for address validation in future connections.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 60.00000% with 8 lines in your changes are missing coverage. Please review.

Project coverage is 93.00%. Comparing base (ff45c18) to head (6cfa555).
Report is 1 commits behind head on main.

Files	Patch %	Lines
dns/quic/_common.py	52.94%	6 Missing and 2 partials ⚠️

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1065      +/-   ##
==========================================
- Coverage   93.89%   93.00%   -0.90%     
==========================================
  Files         143      143              
  Lines       13353    13373      +20     
  Branches     2591     2595       +4     
==========================================
- Hits        12538    12437     -101     
- Misses        479      605     +126     
+ Partials      336      331       -5     

Flag	Coverage Δ
unittests	92.97% <60.00%> (-0.89%)	⬇️

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