Enable the Enable max-len and max-lines eslint rules (#1842)

## Description:

Enable the Enable `max-len` and `max-lines` eslint rules.

Fixes #1785

## Please complete the following:

- [x] I have added screenshots for all UI updates
- [x] I process any text displayed to the user through translateText()
and I've added it to the en.json file
- [x] I have added relevant tests to the test directory
- [x] I confirm I have thoroughly tested these changes and take full
responsibility for any bugs introduced

src/client/UsernameInput.ts

@@ -43,12 +43,17 @@ export class UsernameInput extends LitElement {
         @change=${this.handleChange}
         placeholder="${translateText("username.enter_username")}"
         maxlength="${MAX_USERNAME_LENGTH}"
-        class="w-full px-4 py-2 border border-gray-300 rounded-xl shadow-sm text-2xl text-center focus:outline-none focus:ring-2 focus:ring-blue-500 focus:border-blue-500 dark:border-gray-300/60 dark:bg-gray-700 dark:text-white"
+        class="w-full px-4 py-2 border border-gray-300 rounded-xl shadow-sm
+        text-2xl text-center focus:outline-none focus:ring-2
+        focus:ring-blue-500 focus:border-blue-500 dark:border-gray-300/60
+        dark:bg-gray-700 dark:text-white"
       />
       ${this.validationError
         ? html`<div
             id="username-validation-error"
-            class="absolute z-10 w-full mt-2 px-3 py-1 text-lg border rounded bg-white text-red-600 border-red-600 dark:bg-gray-700 dark:text-red-300 dark:border-red-300"
+            class="absolute z-10 w-full mt-2 px-3 py-1 text-lg border rounded
+            bg-white text-red-600 border-red-600 dark:bg-gray-700
+            dark:text-red-300 dark:border-red-300"
           >
             ${this.validationError}
           </div>`