BADGERS-575: [BREAKING] Audio Described Unification

[ShiningTrapez]

📺 What
Allows for Replacing Sources in a set up BSP session, adds infrastructure around this to allow for using this mechanism for a generic Audio Described solution. This method requires a seperate set of sources to be passed in in a new audioDescribed block, rather than using a combined manifest as the MSE Implementation. Both mechanisms can be controlled via the same API Functions, now called audioDescribed instead of broadcastMixAD, the mechanism used will be selected based on the provided sources, with the generic approach taking precedence if both an audioDecribed block and Manifest containing Audio Described tracks is present.

🛠 How
Overwrite the variable in flight and then reload manifest