souphttpsrc: properly track redirections

souphttpsrc: properly track redirections

The current code configures libsoup to handle redirections
transparently, without informing the caller, thus preventing the element
to record the redirect code and location uri.

Fix this by always setting the SOUP_MESSAGE_NO_REDIRECT, preventing
libsoup from handling the redirection. When we receive a redirection
request and libsoup can safely handle it, return a custom error which
triggers a retry with the new URI.

https://bugzilla.gnome.org/show_bug.cgi?id=777222