Add opentracing provider

[XSAM]

Split from #312.

@bwplotka @yashrsharma44 PTAL

[codecov-commenter]

Codecov Report

Merging #492 (90be9c6) into v2 (6e2c2ac) will decrease coverage by 25.52%.
The diff coverage is 50.46%.

❗ Current head 90be9c6 differs from pull request most recent head 75eeeba. Consider uploading reports for the commit 75eeeba to get more accurate results

@@             Coverage Diff             @@
##               v2     #492       +/-   ##
===========================================
- Coverage   84.01%   58.48%   -25.53%     
===========================================
  Files          30       30               
  Lines         932     1573      +641     
===========================================
+ Hits          783      920      +137     
- Misses        110      590      +480     
- Partials       39       63       +24     

Impacted Files	Coverage Δ
chain.go	0.00% <ø> (-90.91%)	⬇️
interceptors/auth/auth.go	100.00% <ø> (ø)
interceptors/ratelimit/ratelimit.go	60.00% <0.00%> (-40.00%)	⬇️
interceptors/recovery/options.go	78.57% <ø> (ø)
metadata/single_key.go	60.00% <ø> (ø)
testing/testpb/interceptor_suite.go	0.00% <0.00%> (ø)
testing/testpb/test.manual_validator.pb.go	0.00% <0.00%> (ø)
util/backoffutils/backoff.go	60.00% <ø> (ø)
wrappers.go	66.66% <ø> (-33.34%)	⬇️
interceptors/reporter.go	45.45% <20.00%> (-17.05%)	⬇️
... and 27 more

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[bwplotka]

Thanks! Amazing. Let's merge and iterate 👍🏽