expose the QUIC version of a connection

[MarcoPolo]

We already track the QUIC version in a connection. This simply exposes this in the public interface.

[marten-seemann]

LGTM, but let's call this Version instead of QUICVersion.

[codecov]

Codecov Report

Base: 85.49% // Head: 85.48% // Decreases project coverage by -0.01% ⚠️

Coverage data is based on head (559d22e) compared to base (7b211d6).
Patch coverage: 0.00% of modified lines in pull request are covered.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3620      +/-   ##
==========================================
- Coverage   85.49%   85.48%   -0.01%     
==========================================
  Files         142      142              
  Lines       10294    10295       +1     
==========================================
  Hits         8800     8800              
- Misses       1109     1110       +1     
  Partials      385      385              

Impacted Files	Coverage Δ
connection.go	76.35% <0.00%> (-0.07%)	⬇️
interface.go	0.00% <ø> (ø)

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[marten-seemann]

LGTM, but CI is unhappy (not gofmt-ed).

[MarcoPolo]

Should we make the version numbers non-internal? https://github.com/lucas-clemente/quic-go/blob/master/internal/protocol/version.go#L19

[marten-seemann]

Should we make the version numbers non-internal? https://github.com/lucas-clemente/quic-go/blob/master/internal/protocol/version.go#L19

It already is, there's an alias in the quic package. We should probably use that one.

[MarcoPolo]

ah I can't believe I didn't see that at the top of the file.

Does this PR win for most back and forths relative to the code change?