ipahostgroup: Fix documentation sections and agument spec

ansible-test with ansible-2.14 is adding a lot of new tests to ensure
that the documentation section and the agument spec is complete. Needed
changes:

DOCUMENTATION section

- `type: str` needs to be set for string parameters
- `type: list` needs to be set for list parameters
- `elements: str` needs to be given for list of string parameters
- `required` tags need to be fixed according to the `argument_spec`

argument_spec

- `elements="str"` needs to be added to all list of string parameters

The `copyright` date is extended with `-2022`.