* fix: Reinitialize rtcstats when the config changes

The mobile app does not exit after the user has left the meeting. This
means we need to re-initialize rtcstats every time a user joins a call to
be sure we are using the correct deployment information.

* Wrap the sendStats method.

* Uses lighter syntax.

* Fixes the linter and adds a warning.

* Bind the `statsEntry` callback to `this`.

* Removes obsolette comment.