fix(UI): add playsinline attr for video element

> playinline attr needs to be set to true to stop local video from playing in full screen mode in Safari on iOS.
> This applies to the local video thumbnails and the camera previews from the device selection menu and video preview button

react/features/settings/components/web/video/VideoSettingsContent.js

@@ -167,6 +167,7 @@ class VideoSettingsContent extends Component<Props, State> {
                 <div className = 'video-preview-overlay' />
                 <Video
                     className = { videoClassName }
+                    playsinline = { true }
                     videoTrack = {{ jitsiTrack }} />
             </div>
         );