Add new proof of access put logic

Add new APIs to ManagedStorage which allow a caller to "upload" a file by proving they have access to it, without needed to upload the whole file. They ask to put a file (supplying the checksums for the entire file) and are prompted to respond with checksums from a random byte range in the file. If the checksums match, then the put succeed as if the whole file were uploaded.
I don't find these names very descriptive (request is very generic). Just my opinion, but I'd prefer:
 - ClaimForEnvironment (make a claim of ownership on a resource)
 - returns ClaimChallenge
 - client responds with ClaimChallengeResponse