feat: add more accessibility labels

Adds more accessibility labels required for mobile automated testing.

react/features/base/react/components/native/Container.js

      */
     render() {
         const {
+            accessibilityLabel,
+            accessible,
             onClick,
             touchFeedback = onClick,
             visible = true,
                     touchFeedback
                         ? TouchableHighlight
                         : TouchableWithoutFeedback,
-                    { onPress: onClick },
+                    {
+                        accessibilityLabel,
+                        accessible,
+                        onPress: onClick
+                    },
                     element);
         }
 

react/features/conference/components/Conference.native.js

     render() {
         return (
             <Container
+                accessibilityLabel = 'Conference'
+                accessible = { false }
                 onClick = { this._onClick }
                 style = { styles.conference }
                 touchFeedback = { false }>

react/features/toolbox/components/ToolbarButton.native.js

     _renderButton(children) {
         const props = {};
 
+        'accessibilityLabel' in this.props
+            && (props.accessibilityLabel = this.props.accessibilityLabel);
         'disabled' in this.props && (props.disabled = this.props.disabled);
         'onClick' in this.props && (props.onPress = this._onClick);
         'style' in this.props && (props.style = this.props.style);

react/features/toolbox/components/Toolbox.native.js

                     onClick = { this._onToggleAudio }
                     style = { audioButtonStyles.style } />
                 <ToolbarButton
+                    accessibilityLabel = 'Hangup'
                     iconName = 'hangup'
                     iconStyle = { styles.whitePrimaryToolbarButtonIcon }
                     onClick = { this.props._onHangup }