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.

web_src/js/modules/stores.ts

@@ -1,6 +1,7 @@
 import {reactive} from 'vue';
+import type {Reactive} from 'vue';
 
-let diffTreeStoreReactive;
+let diffTreeStoreReactive: Reactive<Record<string, any>>;
 export function diffTreeStore() {
   if (!diffTreeStoreReactive) {
     diffTreeStoreReactive = reactive(window.config.pageData.diffFileInfo);