[latexqc] Continue the ESM migration (#24743)

* Set `"type": "module"` in package.json

* Update imports to include file extensions

* Update imports to include file extensions in test files

* Convert webpack files to ESM

* Update configureStore.js for ESM

* Make static-assets CJS, and rename with .cjs

* Misc: update imports to `node:path`

* Add vitest; Remove chai, mocha, sinon, expect, jsdom

* Return promises in conversion-controller, to make testing easier

* Update tests to vitest syntax

* Fix JSON import syntax and babel config

* Import combobo from NPM

* Rename `app.js` to `app.cjs`

This should prevent errors in the production app (https://console.cloud.google.com/cloud-build/builds;region=us-east1/8b42465c-0d07-4a08-b856-aa18c13fae46?project=overleaf-ops)

### Before

```
node@ea395ce612a8:/overleaf/services/latexqc$ node app.js
[...]
ReferenceError: require is not defined in ES module scope, you can use import instead
This file is being treated as an ES module because it has a '.js' file extension and '/overleaf/services/latexqc/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at file:///overleaf/services/latexqc/app.js:2:1
    at ModuleJob.run (node:internal/modules/esm/module_job:234:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:473:24)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:122:5)
```

### After

```
node@ea395ce612a8:/overleaf/services/latexqc$ node app.cjs
--------------------------
===>  😊 Starting Server . . .
===>  Environment: production
===>  Listening on port: 8082
--------------------------
```

* Rename `app.js` to `app.cjs` (Fixup forgotten one)

* Rename `app.js` to `app.cjs` (Fixup 2)

* Rename asset files to `.js`

Fixes:
```
Refused to execute script from 'https://staging-latexqc.ieee.org/assets/9d6cc24692a7f912ff06.cjs' because its MIME type ('application/octet-stream') is not executable, and strict MIME type checking is enabled.
```
GitOrigin-RevId: f0b618f7fc4062fb6bdc3779dfc5defc5f72d614