Maximum file size on deploy

[nearnshaw]

Limit the size of individual files when deploying.

No file of any extension can weigh more than 50 MB. Although the total scene has a limit of 15 MB per parcel, scenes with multiple parcels can go way overboard.

The CLI should show a clear warning when a scene goes over this limit, indicating what file and how large it is.
This should not affect existing scenes, only the deployment of new ones from now on

We should document this too in the scene limitations doc