refactor: enhanced Join Private Lobby form

[Nonolanlan1007]

Description:

This pull request enhances the JoinLobbyModal component by using the <form> component and the @submit event. It allows the user to use the enter (return) key to submit instead of grabbing its mouse to click on "Join Lobby".
It also introduces a new submit argument to the Button component.

Please complete the following:

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

Please put your Discord username so you can be contacted if a bug or regression is found:

@nolhan__

PS: The tests from tests/InputHandler.test.ts are failing on both main and my branch. EDIT: They no longer fail through the workflow so I guess I didn't have the correct environment

[CLAassistant]

All committers have signed the CLA.