Feature: Update CLI for group creation to use explicit option names for group owner properties

[nicholasyager]

This PR updates the CLI options for group owner creation. Whereas before we required the user to provide the name of the field being updated and the value, now we have explicit properties for --owner-name and --owner-email. Additional properties are also still accepted via the --owner-properties option, which parses a YAML string.

Old syntax:

dbt-meshify group \
  --owner name dave \
  --owner email dave@example.org \
  --owner foo bar \
  test_group_2 

New syntax:

dbt-meshify group \
  --owner-name dave \
  --owner-email dave@example.org \
  --owner-properties '{foo: bar}' \
  test_group_2 

Along the way, I also added an owner decorator that performs validation of --owner-* arguments to ensure that either a name or email is always provided (as per spec), and moved click decorator definitions to cli.py.

Resolves: #65

[dave-connors-3]

🦞