fix(cli): allow passing in group name and refering to list by id

[agschrei]

This PR addresses #99 by adding two new options to the "monitoringlist import" click command:

• an id option to allow referring to existing monitoring lists by ID
• a group option to allow declaring the organization group a monitoring list should be created in

The PR also adds unit tests that mock HTTP calls to verify the expected behavior.

I have tested my PR against portal.vilocify.com and have found it to work as desired.

[woefe]

Hi @agschrei thanks for the PR and the bug report ❤️ I prefer not to mix the monitoring list identification with the --group param in the same PR. I created #103 as a followup for the identification parameters. The API release deployed to prod next week will introduce a groups endpoint, which will be used in #102

LMK, if you find time to update your PR to tackle only #103. I'd also be interested in your input to refine the proposals in #103.