fix: relaxed condition to check if resource exists

The original (`fs-extra`-based) implementation did not check if the
file is writable either.

Resources are not writable in mounted AppImages.

Closes #1586

Signed-off-by: Akos Kitta <a.kitta@arduino.cc>

arduino-ide-extension/src/node/sketches-service-impl.ts

@@ -660,7 +660,7 @@ export class SketchesServiceImpl
 
   private async exists(pathLike: string): Promise<boolean> {
     try {
-      await fs.access(pathLike, constants.R_OK | constants.W_OK);
+      await fs.access(pathLike, constants.R_OK);
       return true;
     } catch {
       return false;