Add Carbon Black Cloud manager. Add fetch_alerts

[avanbrunt-cb]

Pull request checklist

Please check if your PR fulfills the following requirements:

• [x] Docs have been reviewed and added / updated if needed (for bug fixes / features)
• [x] Tests have been added that prove the fix is effective or that the feature works.
• [x] New and existing tests pass locally with the changes.
• [x] Code follows the style guidelines of this project (PEP8, clean code).
• [x] Linter has passed locally and any fixes were made for failures.
• [x] A self-review of the code has been done.

Pull request type

Please check the type of change your PR introduces:

• [ ] Bugfix
• [x] Feature
• [ ] Code style update (formatting, renaming)
• [x] Refactoring (no functional changes, no api changes)
• [ ] Build related changes
• [ ] Documentation content changes (not tied to bugs/features)
• [ ] Other (please describe):

What is the ticket or issue number?

CBAPI-4457

Pull Request Description

Adding Carbon Black Cloud manager and fetch_alerts function

Does this introduce a breaking change?

• [ ] Yes
• [x] No

How Has This Been Tested?

Unit tests