Add propagation API

[dyladan]

This is the first step toward #777. After this, all call-sites will still need to be updated to use the new API.

[codecov-io]

Codecov Report

Merging #797 into master will decrease coverage by 0.29%.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           master    #797     +/-   ##
========================================
- Coverage    94.2%   93.9%   -0.3%     
========================================
  Files         245     185     -60     
  Lines       10660    6676   -3984     
  Branches     1042     630    -412     
========================================
- Hits        10042    6269   -3773     
+ Misses        618     407    -211

Impacted Files	Coverage Δ
...kages/opentelemetry-metrics/test/mocks/Exporter.ts	33.33% <0%> (-16.67%)	⬇️
...opentelemetry-base/test/resources/resource.test.ts	100% <0%> (ø)	⬆️
...s/opentelemetry-metrics/test/MeterProvider.test.ts	100% <0%> (ø)	⬆️
...pe-async-hooks/test/AsyncHooksScopeManager.test.ts	100% <0%> (ø)	⬆️
...-api/src/context/propagation/NoopHttpTextFormat.ts	100% <0%> (ø)	⬆️
...-metrics/test/export/ConsoleMetricExporter.test.ts	100% <0%> (ø)	⬆️
...opagator-jaeger/test/JaegerHttpTraceFormat.test.ts	100% <0%> (ø)	⬆️
...opentelemetry-api/src/metrics/NoopMeterProvider.ts	100% <0%> (ø)	⬆️
packages/opentelemetry-plugin-mongodb/src/types.ts
packages/opentelemetry-plugin-mysql/src/utils.ts
... and 63 more

[mayurkale22]

lgtm

[mayurkale22]

@open-telemetry/javascript-approvers we need more reviews on this one!

[markwolff]

nit: consistency with using public keyword

[dyladan]

to be clear, we want to always use or never use?

[Flarna]

Maybe I'm not understanding this fully but I miss the Composite Propagator. Or is this added by a separate PR?

[dyladan]

Maybe I'm not understanding this fully but I miss the Composite Propagator. Or is this added by a separate PR?

Will be a separate PR as the composite propagator is an SDK detail. From the API perspective it is the same as any other propagator.

[OlivierAlbertini]

LGTM

[vmarchaud]

lgtm

[Flarna]

Will be a separate PR as the composite propagator is an SDK detail. From the API perspective it is the same as any other propagator.

Really? API exposes initGlobalPropagator so it's only possible to set the one and only propagator but nothing to add your propagator into list of the composite.

[dyladan]

Will be a separate PR as the composite propagator is an SDK detail. From the API perspective it is the same as any other propagator.

Really? API exposes initGlobalPropagator so it's only possible to set the one and only propagator but nothing to add your propagator into list of the composite.

In your opinion is the composite propagator an API concern or a blocker for this PR? Keep in mind, with this PR we are only adding the propagation API. No code paths are actually using it yet.

[Flarna]

Nope, it's not blocking.