Add license headers across the project

ts/quill/emoji/blot.tsx

@@ -1,3 +1,6 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
 import React from 'react';
 import Parchment from 'parchment';
 import Quill from 'quill';

ts/quill/emoji/completion.tsx

@@ -1,3 +1,6 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
 import Quill from 'quill';
 import Delta from 'quill-delta';
 import React from 'react';

ts/quill/emoji/index.tsx

@@ -1,2 +1,5 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
 export { EmojiBlot } from './blot';
 export { EmojiCompletion } from './completion';

ts/quill/matchImage.ts

@@ -1,3 +1,6 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
 import Delta from 'quill-delta';
 
 export const matchEmojiBlot = (node: HTMLElement, delta: Delta): Delta => {