refactor: replace jQuery with DOM utils for alt and shift key trackers (@MoushufAlam) (monkeytypegame#7266)

### Description
Replaces jQuery usage with DOM utils for alt and shift key trackers.
Scope intentionally kept small per contributing guidelines.


### Checks

- [x] Adding/modifying Typescript code?
  - [x] I have used `qs`, `qsa` or `qsr` instead of JQuery selectors.
- [x] Check if any open issues are related to this PR; if so, be sure to
tag them below.
- [x] Make sure the PR title follows the Conventional Commits standard.
(https://www.conventionalcommits.org for more info)
- [x] Make sure to include your GitHub username prefixed with @ inside
parentheses at the end of the PR title.

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Related to monkeytypegame#7186 

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Author: MoushufAlam

frontend/src/ts/test/alt-tracker.ts

@@ -1,15 +1,15 @@
 export let leftState = false;
 export let rightState = false;
 
-$(document).on("keydown", (e) => {
+document.addEventListener("keydown", (e: KeyboardEvent) => {
   if (e.code === "AltLeft") {
     leftState = true;
   } else if (e.code === "AltRight") {
     rightState = true;
   }
 });
 
-$(document).on("keyup", (e) => {
+document.addEventListener("keyup", (e: KeyboardEvent) => {
   if (e.code === "AltLeft") {
     leftState = false;
   } else if (e.code === "AltRight") {

frontend/src/ts/test/shift-tracker.ts

@@ -4,7 +4,7 @@ import * as KeyConverter from "../utils/key-converter";
 export let leftState = false;
 export let rightState = false;
 
-$(document).on("keydown", (e) => {
+document.addEventListener("keydown", (e: KeyboardEvent) => {
   if (e.code === "ShiftLeft") {
     leftState = true;
     rightState = false;
@@ -14,7 +14,7 @@ $(document).on("keydown", (e) => {
   }
 });
 
-$(document).on("keyup", (e) => {
+document.addEventListener("keyup", (e: KeyboardEvent) => {
   if (e.code === "ShiftLeft" || e.code === "ShiftRight") {
     leftState = false;
     rightState = false;