Convert frontend code to typescript (#31559)

None of the frontend js/ts files was touched besides these two commands
(edit: no longer true, I touched one file in
61105d0618
because of a deprecation that was not showing before the rename).

`tsc` currently reports 778 errors, so I have disabled it in CI as
planned.

Everything appears to work fine.

web_src/js/globals.ts

@@ -0,0 +1,5 @@
+import jquery from 'jquery';
+import htmx from 'htmx.org/dist/htmx.esm.js';
+
+window.$ = window.jQuery = jquery;
+window.htmx = htmx;