Read integration managers from account data

For https://github.com/vector-im/riot-web/issues/4913 / https://github.com/vector-im/riot-web/issues/10161

Relies on the structure defined by [MSC1957](https://github.com/matrix-org/matrix-doc/pull/1957)

This is just the bit of code to parse the user's widgets (while watching for changes) and allow for it to be the default manager.

src/utils/WidgetUtils.js

@@ -340,6 +340,17 @@ export default class WidgetUtils {
         return widgets.filter((widget) => widget.content && widget.content.type === "m.stickerpicker");
     }
 
+    /**
+     * Get all integration manager widgets for this user.
+     * @returns {Object[]} An array of integration manager user widgets.
+     */
+    static getIntegrationManagerWidgets() {
+        const widgets = WidgetUtils.getUserWidgetsArray();
+        // We'll be using im.vector.integration_manager until MSC1957 or similar is accepted.
+        const imTypes = ["m.integration_manager", "im.vector.integration_manager"];
+        return widgets.filter(w => w.content && imTypes.includes(w.content.type));
+    }
+
     /**
      * Remove all stickerpicker widgets (stickerpickers are user widgets by nature)
      * @return {Promise} Resolves on account data updated