Ignore index.html in service worker cache (#522)

Fixes #517

By default, index.html is cached by the service worker. This is
breaks the application if it's hosted behind an authentifying proxy
which requires periodic revalidation of an auth token.
Specifically, once the auth token expires
1. The index.html is still served from the service worker cache.
2. Subsequent requests (e.g for JS resources) are redirected to the
   login page of the proxy.
3. That login page is never displayed to the user as index.html has been
   successfully loaded.
4. All requests but index.html fail, and the app displays a blank page.

This change fixes this behavior by preventing index.html from being
cached by the service worker. With that change, once the auth token from
the proxy expires:
1. The request for index.html is not served from the service worker
   cache.
2. Instead, a network request for index.html is made, and the user is
   properly redirected to the proxy login page.
3. The user logs in, and index.html is served as normal.
4. Subsequent requests (e.g for JS resources) succeed as now the auth
   token has been refreshed.

rollup.config.js

@@ -12,6 +12,7 @@ const baseConfig = createSpaConfig({
   developmentMode: process.env.ROLLUP_WATCH === 'true',
   injectServiceWorker: true,
   workbox: {
+    globIgnores: ['index.html'],
     navigateFallbackDenylist: [/^\/api.*/],
     skipWaiting: false,
     clientsClaim: false,