libcasper: Move everything to the libcasper package

The libcasper package exists to contain libcasper, but for some reason
only the libcap_net service was in the package, with libcasper itself
and the rest of the services being in runtime. Move everything to the
libcasper package, except tests which stay in the tests package.

MFC after: 1 day
Reviewed by: emaste
Sponsored by: https://www.patreon.com/bsdivy
Differential Revision: https://reviews.freebsd.org/D53576