Loader: Basic implementation

[Kossinator]

Implement a basic loader manager for different unity-structures such as Prefabs, Textures and other Resources.

• https://docs.unity3d.com/ScriptReference/Resources.html
• https://docs.unity3d.com/ScriptReference/Resources.Load.html
• https://docs.unity3d.com/ScriptReference/Resources.LoadAll.html
• https://docs.unity3d.com/Manual/StreamingAssets.html