#15 Save/Load System Rework with UI

## Features * Moves logic out of SaveLevelDataComponent and into SaveGameManager * Adds a Save/Load UI * Adds save name and icon For now, there's no actual icon although I'm considering taking a screenshot during the game that would live alongside the save itself. ## Known Issues * I ran into a bug where the player held block from the previous save was following the player at a distance as if it didn't despawn when the player did. I only ran into this once and I'm not sure what caused it.