Toggle your local video and participants bar in Daily's prebuilt UI

Daily has introduced new properties and instance methods to its prebuilt UI, which allows developers to customize video calls without sacrificing too much time. The new properties include `showLocalVideo` and `showParticipantsBar`, which can be set individually or together depending on the use case. Additionally, two new sets of instance methods have been added: `setShowLocalVideo` and `setShowParticipantsBar`, which allow developers to dynamically toggle the display of these UI elements. These new features aim to help customers and Daily's own team quickly build a webinar app with a customizable video call experience.