feat(longtasks): allow callback to add span attributes on collection

[crellison]

Which problem is this PR solving?

• ability to add application-specific context as attributes to longtask spans

Short description of the changes

This adds a callback parameter to the LongTaskInstrumentation to be executed when a longtask is observed. The return value of the callback is an object of span attributes to be attached to the longtask span.

This feature is important for web applications, as additional details on application state may be relevant to long tasks and can help in correlating long tasks with slow code. This feature allows sites using client-side navigation to add window location details to spans and enables hydrating spans with relevant information from application state.

Checklist

• Ran npm run test-all-versions for the edited package(s) on the latest commit if applicable. (not applicable, but checking it rather than removing)

[linux-foundation-easycla]

The committers are authorized under a signed CLA.

• ✅ Cole Ellison (6be2d11)

[codecov]

Codecov Report

Merging #863 (2f1ddd8) into main (b9a1381) will increase coverage by 0.61%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #863      +/-   ##
==========================================
+ Coverage   95.29%   95.91%   +0.61%     
==========================================
  Files          10       13       +3     
  Lines         701      856     +155     
  Branches      142      178      +36     
==========================================
+ Hits          668      821     +153     
- Misses         33       35       +2     

Impacted Files	Coverage Δ
...y-instrumentation-long-task/src/instrumentation.ts	94.73% <100.00%> (ø)
...ation-user-interaction/src/enums/AttributeNames.ts
...y-instrumentation-long-task/src/instrumentation.ts
...umentation-user-interaction/src/instrumentation.ts
...strumentation-document-load/src/instrumentation.ts
...trumentation-document-load/src/enums/EventNames.ts
...entation-document-load/src/enums/AttributeNames.ts
...lemetry-instrumentation-document-load/src/utils.ts
...strumentation-document-load/src/instrumentation.ts	98.79% <0.00%> (ø)
...entation-document-load/src/enums/AttributeNames.ts	100.00% <0.00%> (ø)
... and 8 more

[blumamir]

Thanks @crellison for addressing everything 💯
This is great work.
Added last minor comment and then it can be merged as far as I am concerned

[blumamir]

LGTM.
Thanks for the contribution :)

I'll be happy for another review from someone with stronger web instrumentation background
@open-telemetry/javascript-approvers

[crellison]

@blumamir Do you have a way of checking in with any of the JS approvers to see if someone is available to review?

[blumamir]

@blumamir Do you have a way of checking in with any of the JS approvers to see if someone is available to review?

I suggest writing in the otel-js CNCF slack channel.
@dyladan - Who from the approvers is most familiar with the web instrumentations?

[rauno56]

@t2t2, the component owner, has approved, I think we are good to go, unless @crellison wants to address the nit above.

[mwear]

LGTM

[dyladan]

@dyladan - Who from the approvers is most familiar with the web instrumentations?

Probably @MSNev at this point. @vmarchaud has more web experience than me. Bart was the person who did most of our web reviews before.