This commit adds the download, extract, patch, build, and install of the Universal Scene Description (USD) library to the install_deps.sh script.
It also changes where $BUILDTOOL install will try and find the USD JSON files. The new method uses ${USD_LIBRARY_DIR}, which should be correct in all cases.
Adding @Ray Molenkamp (LazyDodo) as reviewer to look at the use of ${USD_LIBRARY_DIR} to find the JSON files on Windows.