fix: forward onBodySent/onRequestSent through interceptor handlers

[adarshx01]

Fixes #5695.

Request only calls onBodySent / onRequestSent when those methods exist on the handler. DecoratorHandler defined onBodySent as a no-op, so the chunk was swallowed, and onRequestSent was missing entirely. RetryHandler, RedirectHandler, and CacheHandler wrap the user handler themselves and never forwarded either hook.

Composing interceptors.retry(), redirect(), cache(), or anything that extends DecoratorHandler therefore silently dropped both callbacks. They now pass through the same way onRequestStart already does.

Test plan

• node --test test/decorator-handler.js test/interceptors/body-sent-hooks.js
• Bare Client still fires both hooks
• Same after DecoratorHandler, interceptors.retry(), interceptors.cache(), and interceptors.redirect()

Made with Cursor

[mcollina]

lgtm

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.47%. Comparing base (f387057) to head (4332410).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5696   +/-   ##
=======================================
  Coverage   93.47%   93.47%           
=======================================
  Files         110      110           
  Lines       38846    38876   +30     
=======================================
+ Hits        36310    36341   +31     
+ Misses       2536     2535    -1     

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