Create an SDK checklist for Spotlight readiness

We need a checklist to make sure each SDK is in great shape for Spotlight integration. Will keep updating this list below:

Ensure the SDK can be initialized without a DSN when spotlight is turned on
Support spotlight config variable with custom URL
Support SENTRY_SPOTLIGHT env variable for enabling Spotlight with the same semantics of spotlight config variable (bool + string)
Ensure there's a log message indicating Spotlight is active at a specific URL
Ensure all possible integrations are force-enabled for Spotlight events
Ensure "source context" is working properly
Ensure all available request data is sent to Spotlight
If profiling is available, ensure it is turned on (future need, not needed right now)
Ensure PII scrubbing does not apply to events sent to Spotlight

getsentry / spotlight