Refactor network module to accept free-form config maps

Replace hypervisor_parent/witness_parent strings with hypervisor_config
and witness_config map(string) variables, matching the pattern already
used by the storage module. incus_networks in the root module is updated
from map(number) to map(object) carrying type and the two config maps.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

incus/network.tf

@@ -1,8 +1,11 @@
 module "network" {
-  source      = "./modules/network"
-  for_each    = var.incus_networks
-  name        = each.key
-  hypervisors = toset(keys(var.incus_hypervisors))
-  witnesses   = toset(keys(var.incus_witnesses))
+  source            = "./modules/network"
+  for_each          = var.incus_networks
+  name              = each.key
+  type              = each.value.type
+  hypervisors       = toset(keys(var.incus_hypervisors))
+  witnesses         = toset(keys(var.incus_witnesses))
+  hypervisor_config = each.value.hypervisor_config
+  witness_config    = each.value.witness_config
 }