feat(instrumentation-fetch): Add applyCustomAttributesOnSpan option

[niekert]

This PR adds an applyCustomAttributesOnSpan function on the instrumentation-fetch package. similar to the API of http(s) plugins.

Fixes #1287

Happy to make changes in tests or implementation if needed

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Niek Kruse (bb62ad3, 14e5103)

[codecov]

Codecov Report

Merging #2071 (c4a715d) into main (90a4b4d) will increase coverage by 0.59%.
The diff coverage is 90.90%.

❗ Current head c4a715d differs from pull request most recent head e37cdd8. Consider uploading reports for the commit e37cdd8 to get more accurate results

@@            Coverage Diff             @@
##             main    #2071      +/-   ##
==========================================
+ Coverage   92.14%   92.73%   +0.59%     
==========================================
  Files         120      137      +17     
  Lines        3958     4915     +957     
  Branches      809     1015     +206     
==========================================
+ Hits         3647     4558     +911     
- Misses        311      357      +46     

Impacted Files	Coverage Δ
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	98.65% <90.90%> (ø)
...ation-xml-http-request/src/enums/AttributeNames.ts	100.00% <0.00%> (ø)
...ry-context-zone-peer-dep/src/ZoneContextManager.ts	85.18% <0.00%> (ø)
...es/opentelemetry-context-zone-peer-dep/src/util.ts	100.00% <0.00%> (ø)
packages/opentelemetry-web/src/types.ts	100.00% <0.00%> (ø)
...emetry-instrumentation-xml-http-request/src/xhr.ts	96.90% <0.00%> (ø)
...mentation-xml-http-request/src/enums/EventNames.ts	100.00% <0.00%> (ø)
...kages/opentelemetry-exporter-collector/src/util.ts	100.00% <0.00%> (ø)
...ry-exporter-collector/src/CollectorExporterBase.ts	92.30% <0.00%> (ø)
...-instrumentation-fetch/src/enums/AttributeNames.ts	100.00% <0.00%> (ø)
... and 11 more

[niekert]

I don't want to modify existing tests too much but the order of attributes changed so perhaps using attribute keys is more accurate?

[Flarna]

Is it possible to use assert.deepStrictEqual?

[niekert]

It's going to be tricky because of the http.user_agent and http.host attribute depend on the context of the test runner I believe thats why these attributes are not checked for equality.

I could make achange to use deepStrictEqual for span attributes that do not depend on environment though, wdyt?

[niekert]

I've changed it to assert useragent and host separately and use deepStrictEqual for the other properties 🙏

[niekert]

Reverted the changes to put everything in a new decribe block

[obecny]

lgtm, one final suggestion