ci: initial work for migration-testing (#311)

Also generating new assets for new ci steps.

entc/integration/gremlin/ent/node.go

@@ -25,9 +25,9 @@ type Node struct {
 	// The values are being populated by the NodeQuery when eager-loading is set.
 	Edges struct {
 		// Prev holds the value of the prev edge.
-		Prev *Node
+		Prev *Node `gqlgen:prev`
 		// Next holds the value of the next edge.
-		Next *Node
+		Next *Node `gqlgen:next`
 	} `json:"edges"`
 }