Migrate from vue-cli-service to vite

[phillipthelen]

• Use vite instead of vue-cli-service and webpack
• use vitest for testing
• Remove gulp-nodemon and call node --watch directly
• lazy load some modules (mostly the user-main module inmain.js, which allows Vite to code split better between logged out/logged in, improving load times for the front page and other static pages.
• I ended up also running our image assets through a png optimizer to shrink them, since the transition to Vite ended up bringing some bundle size improvements as well and the png optimizing improves page load times even further 😅