dbus: decode uri when sending PropertiesChanged

Thanks to a bug report in another project, I found that the plasma media player does not decode URIs when displaying data from DBUS.

Sure enough, when no title or album are specified in the DBUS PropertiesChanged message sent by VLC, the media player will instead attempt to resolve these values from the value at xesam:url, as presented below

signal time=1758853278.917195 sender=:1.187 -> destination=(null destination) serial=13 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "Metadata"
         variant             array [
               dict entry(
                  string "mpris:trackid"
                  variant                      object path "/org/videolan/vlc/playlist/3"
               )
               dict entry(
                  string "xesam:url"
                  variant                      string "file:///home/conor/Videos/Screencasts/test_%28video%29.mp4"
               )
               ...
            ]
      )
      ...

Other media players, such as the Dragon media player, will present an unencoded url for use by potential listeners, as seen below. So I don't believe there is any issue with VLC doing the same.

signal time=1759292337.335455 sender=:1.540 -> destination=(null destination) serial=30 path=/org/mpris/MediaPlayer2; interface=org.freedesktop.DBus.Properties; member=PropertiesChanged
   string "org.mpris.MediaPlayer2.Player"
   array [
      dict entry(
         string "CanSeek"
         variant             boolean false
      )
      dict entry(
         string "Metadata"
         variant             array [
               dict entry(
                  string "mpris:trackid"
                  variant                      object path "/org/kde/dragonplayer/tid_82c8fed0442242df7fd1848c1964011a0da3a51a"
               )
               dict entry(
                  string "xesam:url"
                  variant                      string "file:///home/conor/Videos/Screencasts/test_(video).mp4"
               )
            ]
      )
   ]
   array [
   ]

It is also worth noting that this is only a problem for VLC when files are opened a particular way. Opening files from the command line results in an encoded URI, whereas opening files from the QT UI results in only % characters being encoded. This change helps ensure consistency, no matter how a file is opened.