Fix NetworkManager EventTargetParser for Neutron event payload structure

Summary

Fixes the EventTargetParser in NetworkManager to correctly extract resource IDs from Neutron events. The current implementation assumes a flat payload structure with a direct resource_id field, but Neutron uses nested payloads where resources are contained in type-specific objects.

Problem

Current behavior:

resource_id = event_payload['resource_id']  # Always returns nil for Neutron events

Actual Neutron payload structure:

{
  "payload": {
    "network": {
      "id": "b39598c6-e36e-4d8c-82c9-d295addcf82c",
      "tenant_id": "fd2f0bf534504696a8fb62ca84f4e191",
      ...
    }
  }
}

Solution

Key Changes

1. Added resource_type helper:

def resource_type
  @resource_type ||= ems_event.event_type.split(".").first
end

Extracts "network" from "network.create.end" automatically.

2. Added intelligent resource_id extraction:

def resource_id
  @resource_id ||= event_payload.dig(resource_type, "id") || event_payload["resource_id"]
end

• First tries nested structure: payload.dig("network", "id")
• Falls back to direct field for backwards compatibility

3. Replaced if/elsif chain with case statement:

target_type = case resource_type
              when "floatingip" then :floating_ips
              when "router" then :network_routers
              when "network" then :cloud_networks
              ...

4. Enhanced tenant ID extraction:

tenant_id = event_payload['tenant_id'] || 
            event_payload['project_id'] || 
            event_payload.dig(resource_type, 'tenant_id') ||
            event_payload.dig(resource_type, 'project_id') ||
            event_payload.dig('initiator', 'project_id')

Searches multiple locations for tenant/project ID in nested structures.

Testing

Manual testing with real Neutron events via AMQP:

• ✅ Networks, Subnets, Routers, Floating IPs, Security Groups, Ports
• ✅ Resource IDs correctly extracted from nested payloads
• ✅ Tenant IDs correctly extracted from nested structures
• ✅ Targeted refresh working as intended
• ✅ Security group rules (without IDs) correctly trigger full refresh

Updated spec tests:

• Payloads now reflect real Neutron structure (nested objects)
• Added tests for security group rules, fallback scenarios, and tenant extraction