Main Structure & Combat Tab

Made the main GUI and the main framework for the combat tab. Made with React & MUI. Uses the Dashboard Template by MUI. Saving combatants currently does not work. Notes and Search tabs have been added but to not have any functionality. Works on mobile, but some features look weird. All code and structure by @Village10.

Full Changelog: https://github.com/Village10/DM-Helper/commits/v0.1.0