Add user event data from logging extra

[alexmick]

While migrating from raven to sentry-python I noticed my usage of the user key no longer populated the field on the sentry interface :

logger.critical("User error", extra=dict(user=dict(id=123, email="user@example.org")))

This PR is an attempt to bring back this behaviour by adding the user key to the captured event.

I tried to do my best to respect codestyle and conventions but I'm sure this can be further improved. This is more a proof of concept, wasn't sure if it was better to open an issue or and PR so I chose the option with a bit of code 😊

[untitaker]

Sorry, we categorically decided not to do this, here is the rationale: getsentry/sentry-php#844 (comment)

There is also a vague hint as to how a workaround could look like (there are multiple solutions, such as using before_send or push_scope). Let me know if you would like to have a usage example.

[alexmick]

Thanks, I was unaware that it was by design !

You're right, a workaround with push_scope by overriding _emit() in EventHandler or a before_send function on the SDK init work fine 👌