Refactor zipkin/protov2.go

[jan25]

Which problem is this PR solving?

• Related to Support for Zipkin Protobuf spans over HTTP #1695 (comment) (from previously merged PR)

Short description of the changes

• Improve model/ids.go to parse []byte into SpanID/TraceID
• Use model/ids.go in zipkin/protov2.go

[jan25]

crossdock-go test failed, i think its flaky and unrelated to this PR. Is there something we can do to fix that? so CI wouldn't break for any PRs in future

[codecov]

Codecov Report

Merging #1747 into master will increase coverage by <.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1747      +/-   ##
==========================================
+ Coverage   98.35%   98.35%   +<.01%     
==========================================
  Files         194      194              
  Lines        9527     9531       +4     
==========================================
+ Hits         9370     9374       +4     
  Misses        123      123              
  Partials       34       34

Impacted Files	Coverage Δ
cmd/collector/app/zipkin/protov2.go	96.89% <100%> (-0.27%)	⬇️
model/ids.go	100% <100%> (ø)	⬆️

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[yurishkuro]

thanks for the follow-up

[yurishkuro]

Since we're adding a new function, I would prefer to reuse it from Unmarshal(data []byte), e.g.

func (t *TraceID) Unmarshal(data []byte) error {
    var err error
    *t, err = TraceIDFromBytes(data)
    return err
}

Similar for Unmarshal on SpanID

[jan25]

Done. And this change would let func (t *TraceID) Unmarshal parse 8byte long TraceID(Higher 8bytes will be 0)