prepare for draft-32

[marten-seemann]

There are no changes that I didn't backport to draft-29 (as draft-32 and draft-29 are wire-compatible).

This also exposes the versions as aliases in the quic package, so we could say this closes #1271.

[codecov]

Codecov Report

Merging #2831 into master will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #2831      +/-   ##
==========================================
+ Coverage   85.83%   85.83%   +0.01%     
==========================================
  Files         134      134              
  Lines        9030     9036       +6     
==========================================
+ Hits         7750     7756       +6     
  Misses        939      939              
  Partials      341      341              

Impacted Files	Coverage Δ
session.go	77.24% <ø> (ø)
conn_id_generator.go	88.89% <100.00%> (+0.21%)	⬆️
internal/protocol/version.go	100.00% <100.00%> (ø)

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