feat: add SimpleSpanProcessor

[mayurkale22]

Which problem is this PR solving?

• Built-in implementation of SpanProcessor.

Short description of the changes

• This is based on Add SDK span processors spec opentelemetry-specification#205 and split from feat(tracer): implement span processor #149 (to keep PR short and simple).

• SimpleSpanProcessor is one of the built-in span processors which converts the Span to ReadableSpan and passes it to the configured exporter (without any batching).

• Span processors can be registered via a method on SDK Tracer. Example in Java: https://github.com/open-telemetry/opentelemetry-java/blob/861f4e6c551f560c03d69a34829dcdd13461493b/sdk/src/main/java/io/opentelemetry/sdk/trace/TracerSdk.java#L150

• Specs are still pending for that, you can follow the discussion here Add SDK span processors spec opentelemetry-specification#205 (comment)

• It is possible to have multiple exporter on registered SpanProcessor, discussion Add SDK span processors spec opentelemetry-specification#205 (comment)

• I will open another PR to add Batching processor (BatchSpansProcessor).

[OlivierAlbertini]

LGTM

[danielkhan]

@mayurkale22 - is it required from the spec to call it SimpleSampledSpanProcessor? I am wondering because isn't implicit that only sampled spans will be processed?

[mayurkale22]

@mayurkale22 - is it required from the spec to call it SimpleSampledSpanProcessor? I am wondering because isn't implicit that only sampled spans will be processed?

Hmm, ok. I changed it to SimpleSpanProcessor.

[codecov-io]

Codecov Report

Merging #218 into master will decrease coverage by 11.77%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master     #218       +/-   ##
===========================================
- Coverage   94.43%   82.65%   -11.78%     
===========================================
  Files          51       52        +1     
  Lines        1851     1776       -75     
  Branches      122      129        +7     
===========================================
- Hits         1748     1468      -280     
- Misses        103      308      +205

Impacted Files	Coverage Δ
...sic-tracer/test/export/SimpleSpanProcessor.test.ts	100% <100%> (ø)
...try-basic-tracer/src/export/SimpleSpanProcessor.ts	100% <100%> (ø)
...kages/opentelemetry-basic-tracer/test/Span.test.ts	0% <0%> (-100%)	⬇️
...ages/opentelemetry-basic-tracer/src/BasicTracer.ts	22.22% <0%> (-75.93%)	⬇️
packages/opentelemetry-basic-tracer/src/Span.ts	35.59% <0%> (-64.41%)	⬇️
...telemetry-node-tracer/src/instrumentation/utils.ts	95.83% <0%> (-4.17%)	⬇️
...metry-node-tracer/src/instrumentation/constants.ts	100% <0%> (ø)	⬆️
...try-node-tracer/test/instrumentation/utils.test.ts	100% <0%> (ø)	⬆️
...e-tracer/test/instrumentation/PluginLoader.test.ts	100% <0%> (ø)	⬆️
...pentelemetry-basic-tracer/test/BasicTracer.test.ts
... and 2 more

[codecov-io]

Codecov Report

Merging #218 into master will decrease coverage by 11.77%.
The diff coverage is 100%.

@@             Coverage Diff             @@
##           master     #218       +/-   ##
===========================================
- Coverage   94.43%   82.65%   -11.78%     
===========================================
  Files          51       52        +1     
  Lines        1851     1776       -75     
  Branches      122      129        +7     
===========================================
- Hits         1748     1468      -280     
- Misses        103      308      +205

Impacted Files	Coverage Δ
...sic-tracer/test/export/SimpleSpanProcessor.test.ts	100% <100%> (ø)
...try-basic-tracer/src/export/SimpleSpanProcessor.ts	100% <100%> (ø)
...kages/opentelemetry-basic-tracer/test/Span.test.ts	0% <0%> (-100%)	⬇️
...ages/opentelemetry-basic-tracer/src/BasicTracer.ts	22.22% <0%> (-75.93%)	⬇️
packages/opentelemetry-basic-tracer/src/Span.ts	35.59% <0%> (-64.41%)	⬇️
...telemetry-node-tracer/src/instrumentation/utils.ts	95.83% <0%> (-4.17%)	⬇️
...metry-node-tracer/src/instrumentation/constants.ts	100% <0%> (ø)	⬆️
...try-node-tracer/test/instrumentation/utils.test.ts	100% <0%> (ø)	⬆️
...e-tracer/test/instrumentation/PluginLoader.test.ts	100% <0%> (ø)	⬆️
...pentelemetry-basic-tracer/test/BasicTracer.test.ts
... and 2 more