Originally, I just moved the definition of onTranscodingProgress outside of the mediaProcessConfig function: D7475... but on second thought I think we can remove mediaProcessConfig altogether.
Constructing the MediaProcessConfig directly is a lot simpler and removes unnecesary indirection.
(I'm NOT planning any other InputStateContainer refactors. Noticed this because I was looking specifically at processMedia for image avatar work and it was a 2min change)