Feature Request: Enable delayed start with the Camera System to enable other services to initialise it and select a camera

[SimonDarksideJ]

There is a use case where other services may need to decide on which camera should be enabled/activated on launch, e.g. choosing between an ARFoundation or Niantic camera setup.

Solution

• Camera should support the "Auto-Start" behaviour
• System should be able to start the scene without a camera present
• Camera should be "startable" by a call to the Camera system, potentially selecting the Camera Module to start with.