Add OpenTelemetry semantic conventions

[slashmo]

Since we removed the OpenTelemetryTracingSupport library from the main Tracing project in 0.2.0, we should add it to this "extras" repository instead. This frees Swift Distributed Tracing from needing to be up-to-date with the semantic conventions defined in the OpenTelemetry specification.

• [x] #7
• [x] #9
• [x] #8
• [x] #5
• [x] #4
• [x] #10
• [x] #3
• [x] #11
• [x] #14

See Also:

• Swift Distributed Tracing (#53)
• OpenTelemetry Specification: Semantic Conventions

[ktoso]

for reference https://github.com/apple/swift-distributed-tracing/commit/fce1f7c91ad5a733500ea1cdd7ccd7aed9130536

[slashmo]

I'm currently working on this - PR coming soon.

[ktoso]

solves #11

[ktoso]

Very awesome, I think we've done all the main ones for now 🥳