Synchronize flip board checkbox

Fixes https://gitlab.com/kicad/code/kicad/-/issues/5224

pcbnew/tools/pcb_editor_control.cpp

@@ -1573,6 +1573,7 @@ int PCB_EDITOR_CONTROL::FlipPcbView( const TOOL_EVENT& aEvent )
     view()->SetMirror( !view()->IsMirroredX(), false );
     view()->RecacheAllItems();
     frame()->Refresh();
+    frame()->OnDisplayOptionsChanged();
     return 0;
 }
 

pcbnew/widgets/appearance_controls.cpp

@@ -428,6 +428,8 @@ void APPEARANCE_CONTROLS::UpdateDisplayOptions()
     wxASSERT( m_objectSettingsMap.count( LAYER_RATSNEST ) );
     APPEARANCE_SETTING* ratsnest = m_objectSettingsMap.at( LAYER_RATSNEST );
     ratsnest->ctl_visibility->SetValue( options.m_ShowGlobalRatsnest );
+
+    m_cbFlipBoard->SetValue( m_frame->GetCanvas()->GetView()->IsMirroredX() );
 }