Add support for instrumentation scope attributes

[lzchen]

Fixes #815

Note that according to the specs the uniqueness of an InstrumentationScope does not include the attributes.

I am new to Rust and OT-Rust so am ramping up. Please advise if Option<Vec<KeyValue>> is not the correct typing and there's some Rust-specific nuances related to memory management that I have overlooked :)

[codecov]

Codecov Report

Patch coverage: 55.3% and no project coverage change.

Comparison is base (93eae5d) 56.4% compared to head (0a37b69) 56.4%.

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #1021   +/-   ##
=====================================
  Coverage   56.4%   56.4%           
=====================================
  Files        144     144           
  Lines      17717   17752   +35     
=====================================
+ Hits        9997   10017   +20     
- Misses      7720    7735   +15     

Impacted Files	Coverage Δ
opentelemetry-api/src/global/metrics.rs	0.0% <0.0%> (ø)
opentelemetry-api/src/global/trace.rs	28.3% <0.0%> (-0.4%)	⬇️
opentelemetry-api/src/metrics/meter.rs	38.3% <0.0%> (ø)
opentelemetry-api/src/metrics/noop.rs	5.5% <0.0%> (-0.2%)	⬇️
opentelemetry-api/src/trace/mod.rs	87.2% <ø> (ø)
opentelemetry-api/src/trace/noop.rs	52.3% <0.0%> (-0.5%)	⬇️
...elemetry-contrib/src/trace/exporter/jaeger_json.rs	0.0% <0.0%> (ø)
opentelemetry-datadog/src/exporter/mod.rs	24.0% <0.0%> (-0.2%)	⬇️
opentelemetry-jaeger/src/exporter/config/mod.rs	80.8% <0.0%> (-1.3%)	⬇️
opentelemetry-sdk/src/export/trace/stdout.rs	8.1% <0.0%> (-0.2%)	⬇️
... and 7 more

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[lzchen]

@TommyCpp

How does codecov work? Does it run on documentation testing?

[TommyCpp]

LGTM. Thanks 👍

[cijothomas]

LGTM.
Could you add an entry to changelog file as well?
https://github.com/open-telemetry/opentelemetry-rust/blob/main/opentelemetry-api/CHANGELOG.md

[lzchen]

@cijothomas

I haven't seen any other PRs add entries to the CHANGELOG.

@TommyCpp is there a practice for this? Do we populate the CHANGELOG all at once during release or per relevant PR?

[cijothomas]

@cijothomas

I haven't seen any other PRs add entries to the CHANGELOG.

@TommyCpp is there a practice for this? Do we populate the CHANGELOG all at once during release or per relevant PR?

Irrespective of what was done in other PRs, I think all PRs affecting end users should include an entry in changelog as a good practice for any product.

[TommyCpp]

@TommyCpp is there a practice for this? Do we populate the CHANGELOG all at once during release or per relevant PR?

We do have a CHANGELOG for every create. But so far the practice has been one of us collecting all PRs before a release and add them to CHANGELOG

[TommyCpp]

Personally I'd love to require CHANGELOG entry for every PR. Makes release easier

[cijothomas]

Personally I'd love to require CHANGELOG entry for every PR. Makes release easier

I agree. Adding a PR template to encourage changelogs : #1036

[lzchen]

@TommyCpp
Can this be merged?

[TommyCpp]

Will take a look on remaining PRs tonight