fix: Open relevant error when SpotlightMiddleware is on

[BYK]

This fixes an issue with the recent SpotlightMiddleware patch where the error triggered the page was not highlighted/opened automatically. It changes the semapics of capture_event and methods depending on this a bit: we now return the event_id if the error is sent to spotlight even if it was not sent upstream to Sentry servers.

[codecov]

Codecov Report

Attention: Patch coverage is 66.66667% with 4 lines in your changes missing coverage. Please review.

Project coverage is 84.28%. Comparing base (be64348) to head (e262a10).
Report is 1 commits behind head on master.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
sentry_sdk/spotlight.py	0.00%	3 Missing ⚠️
sentry_sdk/client.py	88.88%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #3614   +/-   ##
=======================================
  Coverage   84.27%   84.28%           
=======================================
  Files         133      133           
  Lines       14024    14024           
  Branches     2955     2954    -1     
=======================================
+ Hits        11819    11820    +1     
+ Misses       1465     1464    -1     
  Partials      740      740           

Files with missing lines	Coverage Δ
sentry_sdk/client.py	83.74% <88.88%> (+0.24%)	⬆️
sentry_sdk/spotlight.py	65.57% <0.00%> (ø)