Rename DistributedContext to CorrelationContext

[mayurkale22]

Which problem is this PR solving?

• DistributedContext has been renamed to CorrelationContext, and has kept all its semantics : https://github.com/open-telemetry/opentelemetry-specification/blob/abdd521fdd0f14078976c65f834b8279bfa604f0/specification/api-correlationcontext.md#correlations-api

[codecov-io]

Codecov Report

Merging #834 into master will decrease coverage by 1.81%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #834      +/-   ##
==========================================
- Coverage   94.36%   92.55%   -1.82%     
==========================================
  Files         248      244       -4     
  Lines       10723    10772      +49     
  Branches     1027     1046      +19     
==========================================
- Hits        10119     9970     -149     
- Misses        604      802     +198

Impacted Files	Coverage Δ
packages/opentelemetry-api/src/metrics/Metric.ts	100% <ø> (ø)	⬆️
...kages/opentelemetry-metrics/src/BoundInstrument.ts	100% <ø> (ø)	⬆️
...elemetry-api/src/correlation_context/EntryValue.ts	100% <ø> (ø)
...ackages/opentelemetry-api/src/metrics/NoopMeter.ts	72.09% <0%> (ø)	⬆️
...ry-api/test/noop-implementations/noop-span.test.ts	45.83% <0%> (-54.17%)	⬇️
...-api/test/noop-implementations/noop-tracer.test.ts	47.82% <0%> (-52.18%)	⬇️
...s/opentelemetry-core/test/context/B3Format.test.ts	50% <0%> (-50%)	⬇️
packages/opentelemetry-core/test/utils/url.test.ts	50% <0%> (-50%)	⬇️
...pentelemetry-core/test/internal/validators.test.ts	50% <0%> (-50%)	⬇️
...elemetry-core/test/trace/spancontext-utils.test.ts	55.55% <0%> (-44.45%)	⬇️
... and 51 more