feature: background asset loading

[jcsnider]

Is your feature request related to a problem? Please describe. Currently the client loads textures, audio files, and all other resources as needed, even if in the middle of rendering a frame. These loads impact fps because the game loop waits for the loads to complete. The fps hit can be pretty massive if games reside on standard hard drives

Describe the solution you'd like Background loading of new assets as needed is a must.

Additional context Add any other context or screenshots about the feature request here.

[Arufonsu]

Some ideas:

• Create a separate thread or task to perform the asset loading in the background. This will allow the main game loop to continue running without being blocked by the asset loading process.
• Use a loading screen to inform the player that the game is currently loading assets. This can be as simple as displaying a loading bar or a spinning wheel.
• Use asynchronous loading methods (such as ContentManager.LoadAsync / Load (?) ), to perform the asset loading in the background.