[Super Admin/ Dashboard] implement counters on Dashboard

Implement the following counters on the Dashboard:
- Total organisations
- Total shelters
- Total hosted beneficiaries
- Average shelter capacity
- Total capacity on all shelters
- Total current occupancy 

See design here: https://www.figma.com/design/yxJgmSGcAon2LbzGiHA1sG/OneRoof-(UnAcoperis-redesign)?node-id=3982-6968&t=l8nxwThHkSJrIzuX-4