souphttpsrc: Extract redirection uri on libsoup's restarted callback
souphttpsrc: Extract redirection uri on libsoup's restarted callback

Let libsoup handle redirection automatically.
And then, to figure out redirection uri, extract it on "restarted"
callback which will be fired before soup_session_send() is returned.

https://bugzilla.gnome.org/show_bug.cgi?id=778428

StreamUtils/gst-plugins-good,stfl/gst-plugins-good,GrokImageCompression/gst-plugins-good,GrokImageCompression/gst-plugins-good,hizukiayaka/gst-plugins-good,GrokImageCompression/gst-plugins-good,StreamUtils/gst-plugins-good,GStreamer/gst-plugins-good,hizukiayaka/gst-plugins-good,GStreamer/gst-plugins-good,StreamUtils/gst-plugins-good,hizukiayaka/gst-plugins-good,stfl/gst-plugins-good,pexip/gst-plugins-good,GrokImageCompression/gst-plugins-good,pexip/gst-plugins-good,stfl/gst-plugins-good,hizukiayaka/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,StreamUtils/gst-plugins-good,stfl/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good