feat(nautobotop): add namespace sync support

[abhimanyu003]

This PR introduces full CRUD sync support for Nautobot's IPAM namespace resources. Namespaces can now be synced from ConfigMap-defined YAML into Nautobot via the operator's reconcile loop, following the same reconciliation pattern used for existing DCIM and IPAM resources.

Whats Added.

• Namespaces

Two lookup services were added to support namespace sync:

• TenantService
• TenantGroupService

Sample YAML

Namespaces:

- name: "prod-namespace"
  description: "Production IP namespace"
  location: "US-East-DC1"
  tenant_group: "infrastructure"
  tenant: "network-team"

CR spec additions

The Nautobot custom resource now accepts a new optional ref:

spec:
  namespaceRef:
    - configMapSelector:
        name: namespace-config
        namespace: default