Update Sensor to create and wire label providers for policy evaluation.

Create provider implementations that wrap Sensor's in-memory stores:

Cluster Labels:
- Wrap sensor/common/clusterlabels.Store (in-memory store)
- Already populated from Helm config at sensor startup
- Has Get() method for label lookups

Namespace Labels:
- Wrap sensor/kubernetes/listener/resources/namespace_store.go (in-memory store)
- Stores map[string]*storage.NamespaceMetadata
- Has LookupNamespaceLabels() method (added in ROX-32668)
- Populated from K8s namespace watches

Wire providers through:
1. sensor/common/detector/unified/detector.go:
- Create providers from cluster and namespace stores
- Pass to detection.NewPolicySet() calls (5 locations)

1. sensor/admission-control/manager/manager_impl.go:
   • Create providers from cluster and namespace stores
   • Pass to detection.NewPolicySet() calls (3 locations)

Files:
- NEW: sensor/common/detection/providers.go (provider implementations)
- sensor/common/detector/unified/detector.go (wire providers)
- sensor/admission-control/manager/manager_impl.go (wire providers)

Tests:
Update test files to pass nil providers where label matching isn't tested.

Dependencies:
- Requires ROX-32667 (Central providers) to be merged first
- Leverages ROX-32668 (namespace label storage) and ROX-32151 (cluster label storage)