feat: support for gcs backends (#95)

Author: burnzy

modules/remote-state/data-source.tf

@@ -1,5 +1,5 @@
 locals {
-  data_source_backends   = ["remote", "s3", "azurerm"]
+  data_source_backends   = ["remote", "s3", "azurerm", "gcs"]
   is_data_source_backend = contains(local.data_source_backends, local.backend_type)
 
   remote_workspace = var.workspace != null ? var.workspace : local.workspace
@@ -93,6 +93,11 @@ locals {
       key                  = local.backend.key
     }
 
+    gcs = local.ds_backend != "gcs" ? null : {
+      bucket = local.backend.bucket
+      prefix = local.backend.prefix
+    }
+
   } # ds_configurations
 
 }