ASM: Multi cluster networking

[knee-berts]

changelog

• [x] Created terraform module and cli plumbing for multi-cluster gateway and Anthos service mesh creation
• [x] Removed unused variables from the config.
• [x] Revved all terraform modules and providers to latest.
• [x] Created sample files for MOAR CI
• [x] Added cloud build pipelines for multi-cluster-networking-acm-standalone-vpc.yaml, multi-cluster, acm-shared-vpc.yaml, multi-cluster-shared-vpc.yaml, multi-cluster-acm-standalone-vpc.yaml, multi-cluster-standalone-vpc.yaml, multi-cluster-networking-acm-shared-vpc.yaml sample files

TODO

• Document ASM and MCG