Lexical: Imported core lexical libs

Imported at 0.17.1, Modified to work in-app.
Added & configured test dependancies.
Tests need to be altered to avoid using non-included deps including
react dependancies.

resources/js/wysiwyg/lexical/yjs/CollabLineBreakNode.ts

@@ -0,0 +1,68 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+
+import type {Binding} from '.';
+import type {CollabElementNode} from './CollabElementNode';
+import type {LineBreakNode, NodeKey} from 'lexical';
+import type {Map as YMap} from 'yjs';
+
+import {$getNodeByKey, $isLineBreakNode} from 'lexical';
+
+export class CollabLineBreakNode {
+  _map: YMap<unknown>;
+  _key: NodeKey;
+  _parent: CollabElementNode;
+  _type: 'linebreak';
+
+  constructor(map: YMap<unknown>, parent: CollabElementNode) {
+    this._key = '';
+    this._map = map;
+    this._parent = parent;
+    this._type = 'linebreak';
+  }
+
+  getNode(): null | LineBreakNode {
+    const node = $getNodeByKey(this._key);
+    return $isLineBreakNode(node) ? node : null;
+  }
+
+  getKey(): NodeKey {
+    return this._key;
+  }
+
+  getSharedType(): YMap<unknown> {
+    return this._map;
+  }
+
+  getType(): string {
+    return this._type;
+  }
+
+  getSize(): number {
+    return 1;
+  }
+
+  getOffset(): number {
+    const collabElementNode = this._parent;
+    return collabElementNode.getChildOffset(this);
+  }
+
+  destroy(binding: Binding): void {
+    const collabNodeMap = binding.collabNodeMap;
+    collabNodeMap.delete(this._key);
+  }
+}
+
+export function $createCollabLineBreakNode(
+  map: YMap<unknown>,
+  parent: CollabElementNode,
+): CollabLineBreakNode {
+  const collabNode = new CollabLineBreakNode(map, parent);
+  map._collabNode = collabNode;
+  return collabNode;
+}