Sigmaiq

- Significantly improved the performance of `create_all_and_translate()` from `SigmAIQBackend`
- Added optional filter to exclude specific backends from `create_all_and_translate()`
- Added `black` to dev dependencies
- Added new util to automatically create a `SigmaRule` or `SigmaCollection` object from one of the following types:
- A SigmaRule or SigmaCollection (just returns the object)
- A `str` consisting of valid Sigma rule YAML
- A `dict` consisting of valid Sigma rule JSON
- A `list` containing any of the above types
- Formatted code base with `black`

Fixed pysigma-backend-qradar-aql pinned version causing errors

- Pinned `certifi` version to `2023.07.22` to fix [CVE-2023-37920](https://github.com/advisories/GHSA-xqr8-7jwr-rhp7/dependabot)

New Backend
- Added support for the [Cortex XDR Backend](https://github.com/7RedViolin/pySigma-backend-cortexxdr)!

Updated Backend Versions
- Updated the following backends to the latest version
- pysigma-backend-carbonblack: v0.1.2 -> v0.1.4
- pysigma-backend-elasticsearch: v1.0.3 -> v1.0.5
- pysigma-backend-qradar-aql: v0.1.3 -> v0.1.4
- pysigma-backend-sentinelone: v0.1.1 -> v0.1.2

Bugfixes
- Fixed incorrect relative path of Splunk ES Correlation Search template
- Custom output format "stanza" now works as intended, and will generated a savedsearches.conf file for a correlation search based on the output of the Splunk backend and Sigma Rule description/tags.

Initial pre-release