Added types and method docs to Rollbar and RollbarLogger classes

[danielmorell]

Description of the change

This PR adds typing and comments to the Rollbar and RollbarLogger classes. These two classes are the ones a developer is most likely to interact with the most. Because of that these are the two that need the changes typing and comments the most.

The PR also adds a few updates to the Config class, and fixes an incorrect return type.

The only code change that is not simply handling return types, argument types, or comments is in Rollbar::setLogger(). I had to read the method a few times to make sure I understood exactly what it was doing. I decided to simplify the logic, so it is easier to read and understand.

Lastly

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Related issues

None

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer

[waltjones]

Nice work on setLogger()!