Improve Designer reload upon new release

Currently, the first time we open Studio Designer after deploying a new NOS release, it fetches the new version on background, presenting the user the previous version until a refresh is done. This caching behavior allows us to serve the app faster, but it might prevent a user/customer to perceive the latest changes until he actually reloads the application.

To improve this mechanism, I propose we implement a mechanism to inform the user that a new version of the app was downloaded in background. This method is similar to what other progressive web applications do. We can display a popup with a message informing a new version is available and a button to trigger the refresh. 

An alternative solution might pass to use a token/time-based version to import Designer and avoid such problems.