Add Planner role access to Duo group permissions

Expand the Planner role permissions to have access to the action Use Duo features on GitLab Duo group permissions.

❗ Ensure documentation is updated too. The permissions table should look as follows

Action	Non-member	Guest	Planner	Reporter	Developer	Maintainer	Owner	Notes
Use Duo features			✓	✓	✓	✓	✓	Requires user being assigned a seat to gain access to a Duo add-on.
Configure Duo feature availability						✓	✓
Configure GitLab Duo Self Hosted							✓
Enable beta and experimental features							✓
Purchase Duo seats							✓