Add include_source_context option

[antonpirker]

Problem Statement

Some users do not like the source context to be there and want to disable it.

Solution Brainstorm

For this we need to add a SDK option include_source_context that defaults to True.
If set to false, the source context should not be included.

Here is probably the place where to decide whether to add the source context or not:
https://github.com/getsentry/sentry-python/blob/antonpirker/celery-beat-wo-restart/sentry_sdk/utils.py#L614-L625

[realkosty]

As of right now this can be removed in before_send() as follows:

def before_send(event, hint):
    placeholder = "*** Code context removed in before_send ***"
    for exception in event.get("exception", {}).get("values", []):
        for frame in exception.get("stacktrace", {}).get("frames", []):
            for key in ["pre_context", "post_context"]: # add "context_line" to remove line itself
                if key in frame and type(frame[key]) == list:
                    frame[key] = [placeholder] * len(frame[key]) 

    return event

[sentrivana]

Reopening since there's a bit missing in order to finish the implementation fully.

[antonpirker]

Documentation for this option is still missing, but the option itself is already release in version 1.23.0

[antonpirker]

documentation PR is on the way: getsentry/sentry-docs#7090

So we can close this.