GCP VPC Resource ID Retrieval Support for Include/Exclude Discovery

NetBrain currently does not provide a reliable plugin-based method to retrieve the complete list of discoverable VPC resource IDs for Google Cloud (GCP), which limits the accuracy of include/exclude VPC discovery scoping in GCP environments. This enhancement would introduce a GCP-specific mechanism to fetch and validate discoverable VPC resource IDs, aligning GCP discovery capabilities with those already available for AWS and Azure. Customers managing GCP infrastructure would benefit from more accurate and dependable control over which VPCs are included or excluded during discovery, reducing errors caused by incomplete or outdated resource ID lists.