Add Version func to otel/sdk

[MrAlias]

Towards #3946

Currently the SDK resources report the SDK version as the API version. If a project uses a different version of the SDK than the API this information will be incorrect. Add a version function to the SDK and use it.

[codecov]

Codecov Report

Merging #3949 (b3a6da5) into main (63a0f51) will increase coverage by 0.0%.
The diff coverage is 100.0%.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #3949   +/-   ##
=====================================
  Coverage   81.7%   81.7%           
=====================================
  Files        170     171    +1     
  Lines      12949   12950    +1     
=====================================
+ Hits       10588   10591    +3     
+ Misses      2138    2136    -2     
  Partials     223     223           

Impacted Files	Coverage Δ
sdk/internal/internal.go	100.0% <ø> (ø)
...s/otlp/otlpmetric/internal/transform/metricdata.go	100.0% <100.0%> (ø)
exporters/prometheus/exporter.go	83.7% <100.0%> (ø)
sdk/metric/internal/histogram.go	100.0% <100.0%> (ø)
sdk/metric/metricdata/data.go	57.1% <100.0%> (ø)
sdk/metric/metricdata/metricdatatest/assertion.go	87.3% <100.0%> (+0.2%)	⬆️
...dk/metric/metricdata/metricdatatest/comparisons.go	88.2% <100.0%> (ø)
sdk/resource/builtin.go	90.3% <100.0%> (ø)
sdk/version.go	100.0% <100.0%> (ø)

... and 1 file with indirect coverage changes

[Aneurysm9]

Should there be a distinct version.go for each module? I believe that's what we've done in contrib and rely on multimod to manage them.

[MrAlias]

Should there be a distinct version.go for each module? I believe that's what we've done in contrib and rely on multimod to manage them.

SGTM. The only other place the otel.Version is used, as far as I can tell, is in the OTLP exporters:

opentelemetry-go/exporters/otlp/internal/header.go

Line 23 in f4a9d78

return "OTel OTLP Exporter Go/" + otel.Version()

I could see that being split up and being put in the appropriate modules and each of the modules getting a version.go to track their versions.

I can also see going the same route as contrib with version.go for all modules. Just not sure that is necessary. 🤷

Sounds like good tasks for follow up PRs.

[pellared]

Because of #3949 (comment)

I changed the "Fixed" to "Towards" in the PR description.

I also added a comment to the issue about usage of otel.Version() in OTLP exporters.