OpenTracing Shim: Full multiple parent support.

[carlosalberto]

This includes:

• The Baggage union of ALL parents is used.
• All parents are added as Links, in order to preserve the OpenTracing reference type as an attribute (either CHILD_OF or FOLLOWS_FROM).

Fixes #4906
Fixes #4907

[codecov]

Codecov Report

Base: 90.83% // Head: 90.98% // Increases project coverage by +0.14% 🎉

Coverage data is based on head (e24dcb8) compared to base (21d5597).
Patch coverage: 96.29% of modified lines in pull request are covered.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4916      +/-   ##
============================================
+ Coverage     90.83%   90.98%   +0.14%     
+ Complexity     4857     4830      -27     
============================================
  Files           556      545      -11     
  Lines         14475    14415      -60     
  Branches       1410     1388      -22     
============================================
- Hits          13149    13116      -33     
+ Misses          908      895      -13     
+ Partials        418      404      -14     

Impacted Files	Coverage Δ
...opentelemetry/opentracingshim/SpanBuilderShim.java	88.28% <96.29%> (+10.38%)	⬆️
...metry/extension/aws/AwsConfigurablePropagator.java	0.00% <0.00%> (-100.00%)	⬇️
...try/exporter/zipkin/ZipkinSpanExporterBuilder.java	97.72% <0.00%> (-2.28%)	⬇️
.../java/io/opentelemetry/sdk/resources/Resource.java	90.56% <0.00%> (-1.89%)	⬇️
...telemetry/sdk/trace/export/BatchSpanProcessor.java	91.03% <0.00%> (-1.38%)	⬇️
...opentelemetry/extension/aws/AwsXrayPropagator.java	90.64% <0.00%> (-0.72%)	⬇️
...xporter/internal/okhttp/OkHttpExporterBuilder.java	91.37% <0.00%> (-0.15%)	⬇️
...va/io/opentelemetry/sdk/logs/SdkLoggerBuilder.java	100.00% <0.00%> (ø)
...a/io/opentelemetry/sdk/logs/SdkLoggerProvider.java	100.00% <0.00%> (ø)
...a/io/opentelemetry/sdk/trace/SdkTracerBuilder.java	100.00% <0.00%> (ø)
... and 19 more

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[jack-berg]

Couple of minor suggestions but looks good

[carlosalberto]

Thanks for the review @jack-berg - applied the feedback. The only remaining item is the private access modifier for the (internal) enum ;)