NGF is reloading NGINX for ReferenceGrants with no accepted Gateway

[ciarams87]

Describe the bug
We are reloading after reconciling a ReferenceGrant even when there is no Gateway. This is because we treat every upsert/delete of a ReferenceGrant as a change. This means we will regenerate nginx config every time a ReferenceGrant is created, updated (generation must change), or deleted, even if it does not apply to the accepted Gateway.

To Reproduce
Deploy a ReferenceGrant with no Gateway.

Expected behavior
Config should not be rewritten and NGINX should not be reloaded when no NGINX config changes have occurred.

Your environment
GKE cluster:

• Node count: 3
• Instance Type: e2-medium
• k8s version: 1.27.4-gke.900
• Zone: europe-west2-b
• Total vCPUs: 6
• Total RAM: 12GB
• Max pods per node: 110

NGF deployment:

• NGF version: edge - git commit 72b6c6e
• NGINX Version: 1.25.2

Additional context
See #1116