Add Cache-Control support to uploads, multipart initiate, and presign…

[alexis-]

…ed PUT URLs

• Add an optional cacheControl parameter to the six upload members and InitiateMultipartUploadAsync; null or blank leaves the header unset.
• The multipart path records Cache-Control on the initiate request, since S3 reads object headers from the initiate call and never from parts.
• Add CacheControl to PresignedPutRequest: the header is signed into the URL, so the client must send exactly that value, and R2 stores it on the object.
• The typed value overrides the same header in HeadersToSign, matching the checksum rule.
• Version 2.5.0.