Added Multiplier to Store

Assets/Prefabs/Store/Armor Multiplier.prefab

Assets/Prefabs/Store/Armor Multiplier.prefab.meta

Assets/Prefabs/Store/Damage Multiplier.prefab

Assets/Prefabs/Store/Damage Multiplier.prefab.meta

Assets/Prefabs/Store/Health Multiplier.prefab

Assets/Prefabs/Store/Health Multiplier.prefab.meta

Assets/Prefabs/Store/Mana Cost Multiplier.prefab

Assets/Prefabs/Store/Mana Cost Multiplier.prefab.meta

Assets/Prefabs/Store/Multiplier Prefab.prefab

Assets/Prefabs/Store/Multiplier Prefab.prefab.meta

Assets/Prefabs/Store/Shop Item.prefab

Assets/Scenes/Forest.unity

Assets/Scripts/StatsManager.cs

Assets/Scripts/Upgrades/UpgradeController.cs