Simplify mapdoc remote asset manifest, no need for all these C++ bindings
ResourceCompilerMap: parse the remote asset manifest and symlink mount any transient assets just before `CResourceCompilerMap::CollectMapDependencies`
ResourceCompilerMap: Put the transient asset manifest in the .vpk - this will serve two purposes: publishing should mount before collecitng dependencies of the map, when loading the map locally we need to fetch/mount these transient assets