[UX] Fix all TS build errors

[bocharsky-bw]

In symfony/ux, if you run yarn build there are quite a few ts warnings. This happened because we originally didn't use TypeScript, so when we switched, a lot of "types" were missing.

Partially fixed in symfony/ux#734

[bocharsky-bw]

@weaverryan Hmmm, I'm not sure I converted that ticket into an issue right :) Did I have to create it in "symfony/ux" repo instead? I just saw "ux" in the list and hit it, but seems it was "SymfonyCasts/symfony-ux" repo... too much ux repos I've to mention 😅

[bocharsky-bw]

Completely closed by symfony/ux#735