Don't reset cache while zooming using a gesture (#1103)

* Don't reset cache while zooming using a gesture

This reuses the cached canvas while the gesture is happening. Once it has stop updating, then recompute the cache with the proper zoom.

This should massively improve performance when panning on big scenes on mobile

Fixes #1056

* update snapshot tests

src/appState.ts

@@ -35,6 +35,7 @@ export function getDefaultAppState(): AppState {
     lastPointerDownWith: "mouse",
     selectedElementIds: {},
     collaborators: new Map(),
+    shouldCacheIgnoreZoom: false,
   };
 }