Standardize Async Loading

[STREGA]

Give Entity a state and allow users to check if it's completely loaded

Things that need loaded checking:

• configure() blocks
  • Add a failure check for the async varient
• components with resources
  • Give components a protocol to conform to

Design a LoadingSystem and LoadingSystemComponent with easy access to progress indicator and gracefully handles failure states.
Possibly use a LoadingDescriptionComponent to handle configuring an entity for loading itself.