Rclone third-party copy push

[redblom]

Rclone supports third-party copy push (as per WebDAV COPY specification).
For this to work with the OCM share flow (datatx type share) rclone must pass the tokens for both source and destination accounts with the WebDAV COPY request. The source token will be passed in the authorization header of the COPY request. The destination token will be passed as the userinfo part of the Destination header URI.
The rclone WebDAV COPY request to the source endpoint:

COPY https://reva-src/remote.php/webdav/path-to-file/file.txt
  Authorization: Bearer src-access-token
  Destination: https://dst-access-token@reva-dst/remote.php/webdav/path-to/file.txt

The webdav service at the source end will discover the userinfo part in the Destination URI and use that in the authorization header of the tpc push request.

[update-docs]

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