Add stack information when `stack_info` is set in logging integration.

[antonpirker]

Problem Statement

The stack information should be added to events send with the logging integration when stack_info=True is set.

Code like this should have a stack attached in the resulting event in Sentry:

logger.error(
    "Option %s set to %s. previous update channel: %s",
    key,
    value,
    channel,
    stack_info=True,
)

Solution Brainstorm

Check for the parameter in logging integration and add the stack information if parameter is True.

[antonpirker]

Some info from @untitaker :

exc_info=True should send the stack specifically, it sends the current stack if sys.exc_info is None, otherwise it sends the current exc info stack_info appears to be new in 3.2, we made the api design decisions with py2 in mind at the time