Add Cloud WAF Instance response computed properties

[grokify]

Enhancement to add Cloud WAF Instance read response computed properties for:

1. cloudwaf_instance_id - This maps to the API response id property. The name has been modified for Terraform as id is not an allowed field name. The error is id is a reserved field name for a resource. See more here: id is now a reserved field name in Terraform russellcardullo/terraform-provider-pingdom#11 removed as duplicate to id value.
2. deployment - This maps to the deployment API response property. While this is a JSON object in the API response, this is currently implemented as schema.TypeList with MaxItems set to 1 instead of being a schema.TypeMap due to a limitation in the Terraform Provider Go SDK which requires schema.TypeMap values to be strings. Using a TypeList wil result in deterministic 0-based hash indexes, so a property can be retrieved as deployment.0.dns_entry. This limitation conflicts with implementing deployment.egressIPs which is an array of object. See more here: Add support for maps with non-primitive types (rich / object map support) hashicorp/terraform-plugin-sdk#62