feat(logging): Include exception_name

[michaelbrewer]

Description of changes:

Add exception_name to the logging

Example:

from aws_lambda_powertools import Logger
logger = Logger()

try:
        raise ValueError("something went wrong")
except Exception:
        logger.exception("Received an exception")

Would log out :

{
       "level": "ERROR",
       "location": "<module>:4",
       "message": "Received an exception",
       "timestamp": "2020-08-28 18:11:38,886",
       "service": "service_undefined",
       "sampling_rate": 0.0,
       "exception_name":"ValueError",
       "exception": "Traceback (most recent call last):\n  File \"<input>\", line 2, in <module>\nValueError: something went wrong"
}

Checklist

• Meet tenets criteria
• Update tests
• Update docs
• PR title follows conventional commit semantics

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[heitorlessa]

LGTM - We can add either in this or in another PR a mention that the name of the exception will be available in another record to ease analysis exceptions over time: https://awslabs.github.io/aws-lambda-powertools-python/core/logger/#logging-exceptions

[heitorlessa]

Great to have that one - been long overdue for me too. I'll make a PR before we release it to add a sample in the docs on how to create stats for it :)

Thank you again!