Create metrics endpoints for NFV-related information
Create endpoints:
- GET /osapi/metrics/registeredNsds (currently appearing as "experiments")
- Exp. Resp: { registeredNsds: 32 }
- existing endpoints: /osapi/experiments, /osapi/admin/experiments
- GET /osapi/metrics/registeredVnfs (currently appearing as "vxfs")
- Exp. Resp: { registeredVnfs: 45 }
- existing endpoint: /osapi/admin/vxfs
- GET /osapi/metrics/registeredManoProviders
- Exp. Resp: { registeredManoProviders: 3 }
- existing endpoint: /osapi/admin/manoproviders