chore: improve naming of span related context APIs

[Flarna]

Which problem is this PR solving?

• fixes Naming of span related APIs on context (setExtractedSpanContext(), getParentSpanContext(),...) #1713

Short description of the changes

Rename [gs]etActiveSpan() to [gs]etSpan() as the span is not active anywhere, it's just referenced by the context.

Rename setExtractedSpanContext() to setSpanContext() because any SpanContext may be set not only extracted ones.

Rename getParentSpanContext() to getSpanContext()` because it retrieves the context of the span which can be any span not only a parent.

[sg]etSpanContext() are quite simple wrappers and could be removed to reduce API surface if preferred. But I see not that much maintenance pain of keeping them so I left them in for now.

[codecov]

Codecov Report

Merging #1749 (6956e54) into master (7e5da41) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1749      +/-   ##
==========================================
+ Coverage   92.07%   92.11%   +0.03%     
==========================================
  Files         166      166              
  Lines        5593     5591       -2     
  Branches     1199     1198       -1     
==========================================
  Hits         5150     5150              
+ Misses        443      441       -2     

Impacted Files	Coverage Δ
...ges/opentelemetry-instrumentation-http/src/http.ts	95.49% <ø> (ø)
packages/opentelemetry-plugin-fetch/src/fetch.ts	96.52% <ø> (ø)
packages/opentelemetry-plugin-http/src/http.ts	97.28% <ø> (ø)
packages/opentelemetry-api/src/context/context.ts	91.66% <100.00%> (-0.34%)	⬇️
packages/opentelemetry-api/src/trace/NoopTracer.ts	96.55% <100.00%> (ø)
...y-core/src/context/propagation/HttpTraceContext.ts	100.00% <100.00%> (ø)
...metry-core/src/trace/sampler/ParentBasedSampler.ts	83.87% <100.00%> (ø)
...entelemetry-propagator-b3/src/B3MultiPropagator.ts	100.00% <100.00%> (ø)
...ntelemetry-propagator-b3/src/B3SinglePropagator.ts	100.00% <100.00%> (ø)
...ackages/opentelemetry-shim-opentracing/src/shim.ts	87.70% <100.00%> (ø)
... and 2 more

[vmarchaud]

I think they are heavy debate on the PR about the namespacing which belong to its issue. I'm fine with renaming the helpers and decide later where to export them

[dyladan]

I think they are heavy debate on the PR about the namespacing which belong to its issue. I'm fine with renaming the helpers and decide later where to export them

I agree with @vmarchaud the debate has not much to do with the substance of this PR and the name change is in general good.

[dyladan]

@obecny i see you 👍 the comment but no approval yet

[obecny]

@obecny i see you 👍 the comment but no approval yet

I thought I approved