FRE-600: Fix code review blockers

- Consolidated duplicate UndoManagers to single instance
- Fixed connection promise to only resolve on 'connected' status
- Fixed WebSocketProvider import (WebsocketProvider)
- Added proper doc.destroy() cleanup
- Renamed isPresenceInitialized property to avoid conflict

Co-Authored-By: Paperclip <noreply@paperclip.ing>

node_modules/lodash/_createAssigner.js

@@ -0,0 +1,37 @@
+var baseRest = require('./_baseRest'),
+    isIterateeCall = require('./_isIterateeCall');
+
+/**
+ * Creates a function like `_.assign`.
+ *
+ * @private
+ * @param {Function} assigner The function to assign values.
+ * @returns {Function} Returns the new assigner function.
+ */
+function createAssigner(assigner) {
+  return baseRest(function(object, sources) {
+    var index = -1,
+        length = sources.length,
+        customizer = length > 1 ? sources[length - 1] : undefined,
+        guard = length > 2 ? sources[2] : undefined;
+
+    customizer = (assigner.length > 3 && typeof customizer == 'function')
+      ? (length--, customizer)
+      : undefined;
+
+    if (guard && isIterateeCall(sources[0], sources[1], guard)) {
+      customizer = length < 3 ? undefined : customizer;
+      length = 1;
+    }
+    object = Object(object);
+    while (++index < length) {
+      var source = sources[index];
+      if (source) {
+        assigner(object, source, index, customizer);
+      }
+    }
+    return object;
+  });
+}
+
+module.exports = createAssigner;