feat: Allow to use InferenceProvider CR Name as Provider's Route candidate_id

[mvazquezc]

Problem:
The provider_route filter's candidate_id in each route must match the Grid overlay's stable_id, not the InferenceProvider CR
name. The stable_id is a deterministic short hash generated by the operator (e.g., f91111ba), not a human-readable name like qwen3-ifc1.
When they don't match, the provider gateway returns a silent HTTP 403.

Workaround:

Check the overlay for stable_id values:

oc -n grid-system get configmap grid-overlay-glb-demo-edge-gateway  -o jsonpath='{.data.routing-overlay\.json}' |  python3 -c "import json,sys; [print(c['cluster'],c['stable_id']) for c in json.load(sys.stdin)['overlay']['candidates']]"

Use these stable_id values as the candidate_id in the provider gateway's provider_route config.

Suggested feature:

Accept both stable_id and the InferenceProvider name as candidate_id.