Add 'description' and 'default' fields to 'groups' schema

[BenjMaq]

Description of change

default and description are two fields available in the Zendesk Support API for the groups entity.
They are currently not available in the tap-zendesk schema for groups. This PR is adding them.

Manual QA steps

• Ran tap-zendesk locally

WARNING Removed 2 paths during transforms:
    default
    description
WARNING Removed paths list: ['default', 'description']

• Ran tap-zendesk with branch add_description_default_to_groups_schema locally
  -> No WARNING. All fields, including default and description have been pulled.

Risks

• Very low.

Rollback steps

• Revert this branch