Introduce a top-level Version() and SemVersion() function

[evantorrie]

These are intended to be used by submodules within the repo that need to specify an "instrumentation version" when creating a tracer or meter.

See #214

SemVersion() may not be required (opinions wanted), but it does enable creating a versioned tracer/meter simply while guaranteeing the correct semver: prefix is always applied.

tracer := otelglobal.TracerProvider().Tracer(
			defaultTracerName,
			oteltrace.WithInstrumentationVersion(contrib.SemVersion()),
		)

Bikeshedding on file name and location also welcomed.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ ET (96890ad)

[MrAlias]

This looks good, and I think it should be merged as is (save the minor suggestions/questions).

Going forward we might want to consider keeping the version defined as a const that is updated at build time. I've seen this used before (with the related Makefile) and I think it would help when future bug reports come in. It would be easier to determine if the instrumentation was built from a particular commit or branch instead of a release.

I can open an issue if there any other shared desire to try this later on.

[evantorrie]

Going forward we might want to consider keeping the version defined as a const that is updated at build time. I've seen this used before (with the related Makefile) and I think it would help when future bug reports come in. It would be easier to determine if the instrumentation was built from a particular commit or branch instead of a release.

I can open an issue if there any other shared desire to try this later on.

Yes, I too like having the git shortref in the code, and I'm happy to take on the assignment.

[Aneurysm9]

Yes, I too like having the git shortref in the code, and I'm happy to take on the assignment.

I created #229 to track that enhancement and noted an alternative approach that might work in place of a build-time declaration that would be out of our control.