T2684

Depends on D12021

Add a modal to notify the user that a more recent version of Cashtab is available with a confirmation option that will reload the page and get the latest version.

This implementation is modeled from this summary: https://felixgerschau.com/create-a-pwa-update-notification-with-create-react-app/

npm run build
Deploy the site somehow (I used netlify). Visit the site and verify that there is a service worker by opening the dev console and clicking on Application --> Service Workers
Make a visible change. One of the easiest is to change teh WalletLabel.js component to add a new string after the {name} variable inside <WalletName></WalletName>
npm run build
Deploy the site to the same URL
Give it about a minute. You should see the modal introduced in this diff.
Click 'OK' and the page will reload.
You should be able to see your change on the reloaded page.