Add Asset system

- Add Abstract Asset class which defines Assets
- Add AssetManager class to keep track of all the Asset
- Add AssetFile class to cache the asset without loading it
- Add UUID class to uniquely identify assets
- Add MetaFile class to load meta asset files

CopiumEngine/assets/fox.meta

@@ -0,0 +1,3 @@
+[Texture2D]
+filepath=res/textures/texture.png
+uuid=f49a5284-d666-0982-95ca-cf68cc3d4f45

CopiumEngine/assets/fox2.meta

@@ -0,0 +1,3 @@
+[Texture2D]
+filepath=res/textures/texture2.png
+uuid=0964e525-22c3-4d25-d5c6-a162965f6e8d