Remove and replace Frontend Libraries

[askvortsov1]

Follow-up to https://github.com/flarum/core/issues/1821

Right now, we're considering:

• [ ] jquery => cash (Typescript, better maintained, smaller) + velocity (separate animation library)
• [ ] Stop using bootstrap js
  • [x] Use a composable component for tooltips (#2843)
  • [ ] CSS tooltips instead! (#2697)
• [x] utils/classList => clsx library (we could export this out under utils/classList like we do with utils/Stream?) (#2760)
• [x] Replace lodash-es with our own functions (#2827)
  • [x] throttle -> npm throttle-debounce (#2827)
• [x] Drop spin.js and replace with our own custom loading indicator (#2764)