DAV protocol fixes (Fixes BUGZ-4235)

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This merge request is automatically cherrypicked from !1872 (merged) from source branch https://source.coderefinery.org/slu/arc/-/tree/dav-protocol-fixes orginally made by @slu .
The original MR went to branch: https://source.coderefinery.org/nordugrid/arc/-/tree/next
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Fixes BUGZ-4235. HTTP DMC now implicitly converts dav:// and davs:// URLs to http:// and https:// respectively before sending request to a remote server. Remote server sees https?:// URL in the request and does not get confused with unknown davs?:// scheme.

Correct behavior tested on URLs provided in the ticket.