This is a XGraphicObjectResolver (future) replacement as it will
not be needed anymore. All resolving from URL to URL will be
replaced by loading, saving and serialization of XGraphic objects
(when appropriate), which is covered by this interface and
implementation by XmlGraphicHelper - the same that implements the
XGraphicObjectResolver.

Change-Id: I227634e443ce336218c2a2effaf34f9ef3576382
Reviewed-on: https://gerrit.libreoffice.org/49073Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>
Tested-by: Tomaž Vajngerl <quikee@gmail.com>