Remove defective svn::Path(QUrl) ctor

Summary:
Replace QUrl kio_svnProtocol::makeSvnUrl() with svn::Path kio_svnProtocol::makeSvnPath() - the returned QUrl was converted to svn::Path anyway.

The svn::Path(QUrl) ctor did it wrong - e.g. it did not remove the query part of the url). Since we don't need it anymore, we can remove it :)

Test Plan:
Test kioslave with gwenview - try to open a image from svn.kde.org:

gwenview "ksvn://svn.kde.org/home/kde/trunk/tests/calligratests/interoperability/images/photoshop/Content 001.png"
also test with a local svn repository (ksvn+file:// ...) if available.

Reviewers: cgiboudeaux, dfaure

Reviewed By: dfaure

Differential Revision: https://phabricator.kde.org/D7517