move lib/go/gremlin to ent/dialect (#1192)

Summary:
Pull Request resolved: https://github.com/facebookexternal/fbc/pull/1192

Pull Request resolved: https://github.com/facebookincubator/ent/pull/11

Reviewed By: alexsn

Differential Revision: D16377224

fbshipit-source-id: 07ca7436eb9b64fbe2299568560b91466b2417ba

ent.go

@@ -2,13 +2,10 @@
 package ent
 
 import (
-	"context"
-
+	"fbc/ent/dialect/gremlin/graph/dsl"
 	"fbc/ent/dialect/sql"
 	"fbc/ent/edge"
 	"fbc/ent/field"
-	"fbc/lib/go/gremlin"
-	"fbc/lib/go/gremlin/graph/dsl"
 )
 
 type (
@@ -45,11 +42,6 @@ type (
 		Assoc() *edge.Edge
 	}
 
-	// Execer is the driver for executing gremlin requests.
-	Execer interface {
-		Exec(context.Context, string, interface{}) (*gremlin.Response, error)
-	}
-
 	// Predicate applies condition changes on either graph traversal or sql selector.
 	Predicate struct {
 		SQL     func(*sql.Selector)  // common sql.