all: add license header to all go files

Summary:
Used addlicense to generate this:
 addlicense -c "Facebook Inc" -f license_header .

example was taken from: https://github.com/facebook/litho/blob/master/lib/soloader/BUCK

Reviewed By: alexsn

Differential Revision: D17070152

fbshipit-source-id: e7b91398d7f6181727be3400c1872ad5f28e38ed

dialect/gremlin/graph/dsl/__/dsl.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package __
 
 import "github.com/facebookincubator/ent/dialect/gremlin/graph/dsl"

dialect/gremlin/graph/dsl/dsl.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 // Package dsl provide an API for writing gremlin dsl queries almost as-is
 // in Go without using strings in the code.
 //

dialect/gremlin/graph/dsl/dsl_test.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package dsl_test
 
 import (

dialect/gremlin/graph/dsl/g/g.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package g
 
 import "github.com/facebookincubator/ent/dialect/gremlin/graph/dsl"

dialect/gremlin/graph/dsl/p/p.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package p
 
 import (

dialect/gremlin/graph/dsl/traversal.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package dsl
 
 import (

dialect/gremlin/graph/edge.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (

dialect/gremlin/graph/edge_test.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (

dialect/gremlin/graph/element.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 // Element defines a base struct for graph elements.

dialect/gremlin/graph/valuemap.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (

dialect/gremlin/graph/valuemap_test.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (

dialect/gremlin/graph/vertex.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (

dialect/gremlin/graph/vertex_test.go

@@ -1,3 +1,7 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
 package graph
 
 import (