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/utils/match.ts

@@ -0,0 +1,43 @@
+import emojis from '../../../assets/emoji.json';
+
+const maxMatches = 6;
+
+function sortAndReduce(map) {
+  const sortedMap = new Map(Array.from(map.entries()).sort((a, b) => a[1] - b[1]));
+  return Array.from(sortedMap.keys()).slice(0, maxMatches);
+}
+
+export function matchEmoji(queryText) {
+  const query = queryText.toLowerCase().replaceAll('_', ' ');
+  if (!query) return emojis.slice(0, maxMatches).map((e) => e.aliases[0]);
+
+  // results is a map of weights, lower is better
+  const results = new Map();
+  for (const {aliases} of emojis) {
+    const mainAlias = aliases[0];
+    for (const [aliasIndex, alias] of aliases.entries()) {
+      const index = alias.replaceAll('_', ' ').indexOf(query);
+      if (index === -1) continue;
+      const existing = results.get(mainAlias);
+      const rankedIndex = index + aliasIndex;
+      results.set(mainAlias, existing ? existing - rankedIndex : rankedIndex);
+    }
+  }
+
+  return sortAndReduce(results);
+}
+
+export function matchMention(queryText) {
+  const query = queryText.toLowerCase();
+
+  // results is a map of weights, lower is better
+  const results = new Map();
+  for (const obj of window.config.mentionValues ?? []) {
+    const index = obj.key.toLowerCase().indexOf(query);
+    if (index === -1) continue;
+    const existing = results.get(obj);
+    results.set(obj, existing ? existing - index : index);
+  }
+
+  return sortAndReduce(results);
+}