don't reset specific appState props on canvas clear (#2359)

Co-authored-by: David Luzar <luzar.david@gmail.com>

src/actions/actionCanvas.tsx

@@ -47,6 +47,11 @@ export const actionClearCanvas = register({
       appState: {
         ...getDefaultAppState(),
         appearance: appState.appearance,
+        elementLocked: appState.elementLocked,
+        exportBackground: appState.exportBackground,
+        exportEmbedScene: appState.exportEmbedScene,
+        gridSize: appState.gridSize,
+        shouldAddWatermark: appState.shouldAddWatermark,
         username: appState.username,
       },
       commitToHistory: true,