feat(exporter-zipkin): per-span service name

[sfishel-splunk]

…wn attributes or its resource's attributes

Which problem is this PR solving?

• My use case is instrumenting a frontend single-page-application where I'd like to model different parts of the app as different services from a tracing perspective. But I want all parts of the application to share a single instance of the Zipkin exporter.

Short description of the changes

• When converting the spans to the Zipkin format, check for a service name defined either in the span's attributes or in its resource's attributes, and allow that service name to override the one provided to the exporter constructor.

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Simon Fishel (3e05188, d241930, 9079b08, 8cd349d)

[codecov]

Codecov Report

Merging #1789 (f96fec0) into master (fd0d35d) will decrease coverage by 0.23%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1789      +/-   ##
==========================================
- Coverage   92.60%   92.36%   -0.24%     
==========================================
  Files         174      157      -17     
  Lines        6042     5108     -934     
  Branches     1283     1091     -192     
==========================================
- Hits         5595     4718     -877     
+ Misses        447      390      -57     

Impacted Files	Coverage Δ
...ckages/opentelemetry-exporter-zipkin/src/zipkin.ts	100.00% <100.00%> (ø)
...ages/opentelemetry-exporter-collector/src/types.ts
...kages/opentelemetry-web/src/StackContextManager.ts
...s/opentelemetry-instrumentation-fetch/src/fetch.ts
.../opentelemetry-exporter-collector/src/transform.ts
packages/opentelemetry-web/src/types.ts
...ry-context-zone-peer-dep/src/ZoneContextManager.ts
...mentation-xml-http-request/src/enums/EventNames.ts
...ntelemetry-web/src/enums/PerformanceTimingNames.ts
...ackages/opentelemetry-web/src/WebTracerProvider.ts
... and 8 more

[obecny]

few comments, please add unit test for the changes

[vmarchaud]

Thanks for the contribution @sfishel-splunk !