* Start working on flow logs
* Change test
* Constructing tests
* Changing exceptions and adding more tests
* Adding more tests
* Changing model and adding more tests
* Adding support for tags
* Mocking Access error with non-existing Log Group Name
* Adding FlowLogAlreadyExists support
* Changing style
* Reformatted code
* Reformatted tests
* Removing needless test
* Adding support for CloudFormation
* Reformatting slightly
* Removing arnparse and using split
* Rearranging tests
* Fixing FilterNotImplementedError test
* Moving imports to 'if' clauses and adding explicit test for 'cloud-watch-logs' type
* Setting names matching boto3 API and restoring 'not-implementd-filter' test
* Reformatting tests with black
