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/subtract.js

@@ -0,0 +1,22 @@
+var createMathOperation = require('./_createMathOperation');
+
+/**
+ * Subtract two numbers.
+ *
+ * @static
+ * @memberOf _
+ * @since 4.0.0
+ * @category Math
+ * @param {number} minuend The first number in a subtraction.
+ * @param {number} subtrahend The second number in a subtraction.
+ * @returns {number} Returns the difference.
+ * @example
+ *
+ * _.subtract(6, 4);
+ * // => 2
+ */
+var subtract = createMathOperation(function(minuend, subtrahend) {
+  return minuend - subtrahend;
+}, 0);
+
+module.exports = subtract;