Optional Internal_Sentinel to distinguish a real provider from the default context value.
Get a URL for viewing/downloading a file. Uses client API methods for different resource types:
All distinct resource types present in the cached files
Share files with specified users.
Accepts FileEntry[] (not just fileIds) because cascade resolution needs the
resourceType to determine which files contain references to other files
(e.g. clip-compositions referencing audio clips).
Sharing is two-phase:
File cache context value