Requested feature

Configuration option create_group

Rationale

When the underlying Maxbanton\Cwh\Handler\Cloudwatch instance flushes the logs, it will initialize itself and check if the log group and log stream already exist or create them if they do not.
To prevent this behavior (for example due to limited permissions on AWS), they provide the constructor parameter createGroup which defaults to true -> to source code. It would be beneficial to have this parameter exposed as config option of this log handler so it can be configured on the application level. Currently, the parameter is left unspecified in this library -> to source code

Let me know what you think about this so I might open a pull request in the future.