This provider:
- supports the `X-OC-Mtime` header to set the mtime
- calculates SHA1 checksum server side and returns it as a `ME:sha1hex` prop
To differentiate the new hasMESHA1 quirk, the existing hasMD5 and hasSHA1
quirks for Owncloud have been renamed to hasOCMD5 and hasOCSHA1.
Fixes#6837