Add types to various low-level functions (#31781)

Adds types to various low-level modules. All changes are type-only, no
runtime changes. `tsc` now reports 38 less errors.

One problem was that `@types/sortablejs` does not accept promise return
in its functions which triggered the linter, so I disabled the rules on
those line.

package.json

@@ -107,6 +107,7 @@
     "stylelint-declaration-strict-value": "1.10.6",
     "stylelint-value-no-unknown-custom-properties": "6.0.1",
     "svgo": "3.3.2",
+    "type-fest": "4.23.0",
     "updates": "16.3.7",
     "vite-string-plugin": "1.3.4",
     "vitest": "2.0.5"