[ maintain-harbor ] add job for managing harbor quotas

• add a new manage_harbor_projects_quotas job that runs for all existing projects in harbor, ensuring the project's quota matches the configured quota.
• write tests.

the project quota should now be managed from toolforge-deploy so make sure to update toolforge-deploy before deploying this.

• Important: harbor's system-wide default project quota will still be applied to newly created projects until this job runs (however once this job runs it updates the quotas to match the configured default on toolforge-deploy).

  To change the system-wide default, you need to do so manually as this requires system-admin privileges, which the maintain-harbor robot account does not have.

Depends-on: toolforge-deploy!674 (merged)
Depends-on: builds-builder!66 (merged)
Bug: T352417
Signed-off-by: raymond-ndibe rndibe@wikimedia.org