feat(@opentelemetry-instrumentation-fetch): support reading response body from the hook applyCustomAttributesOnSpan

[echoontheway]

opentelemetry-instrumentation-fetch support reading response body from the hook applyCustomAttributesOnSpan

Which problem is this PR solving?

applyCustomAttributesOnSpan's callback param response has been used, so that we can't get response body.

https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch
UT with current code:

Detail error is as follows,

Short description of the changes

1. return the response.clone() for applyCustomAttributesOnSpan, so that we can read the body from the cloned repsonse.
2. add corresponding unit test

[codecov]

Codecov Report

Merging #2497 (84a9bfd) into main (d3f5163) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #2497   +/-   ##
=======================================
  Coverage   93.23%   93.23%           
=======================================
  Files         137      137           
  Lines        5043     5044    +1     
  Branches     1067     1067           
=======================================
+ Hits         4702     4703    +1     
  Misses        341      341           

Impacted Files	Coverage Δ
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	96.98% <0.00%> (+0.01%)	⬆️

[johnbley]

Hi! Thanks for contributing! Could you first provide a unit test showing the problem (i.e., one that fails without your code changes and passes with them)?

[echoontheway]

Hi! Thanks for contributing! Could you first provide a unit test showing the problem (i.e., one that fails without your code changes and passes with them)?

done~~