Add span start end end options to gin configuration

[dmathieu]

This allows setting span start and end options to the gin configuration, so folks can (for example), enable stack traces to recorded errors.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.2%. Comparing base (f3ba8c2) to head (d598c72).

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #5250   +/-   ##
=====================================
  Coverage   61.2%   61.2%           
=====================================
  Files        185     185           
  Lines      11207   11216    +9     
=====================================
+ Hits        6865    6874    +9     
  Misses      4142    4142           
  Partials     200     200           

Files	Coverage Δ
...ation/github.com/gin-gonic/gin/otelgin/gintrace.go	80.5% <100.0%> (+0.2%)	⬆️
...ntation/github.com/gin-gonic/gin/otelgin/option.go	100.0% <100.0%> (ø)

[pellared]

Similarly to #5251 (review)

The user can e.g. change the span kind using https://pkg.go.dev/go.opentelemetry.io/otel/trace#WithSpanKind or create attributes which are not aligned with the semantic conventions and they others may blame that the instrumentation library does not follow semantic conventions.

However, with the difference that func HTML(c *gin.Context, code int, name string, obj interface{}) { is calling span.RecordError(err) when c.HTML(code, name, obj) panics.

Maybe we should just add an option to capture stacktraces instead?