Add Option to Choose Piece Color

## Description

As of now, the UI is hardcoded to give `white` pieces to whoever starts the game. The Micro-rollup on the other hand takes the `color` input in the `JoinGame` payload.

Extend the UI so the player can choose the color of the pieces. 
The ideal implementation would be a modal that pops up when you click on "Create Game". This modal can later have more fields too.