Support dynamically loading libsoup dependency at runtime
Currently tracker is built against either libsoup2 or libsoup3 and always links to one version.
This is a problem when tracker is pulled in as an indirect dependency such as GTK as it limits all GTK applications to matching the version tracker was built against.
Since trackers usage of libsoup is quite trivial its possible to dynamically detect if any version is already loaded and use that, thus supporting both 2 and 3 just fine.
An example of this done in C is here: https://gitlab.gnome.org/GNOME/glib-networking/-/blob/master/tls/base/gtlshttp.c