Create a library for the kernel consumer

Kconsumerd functionnalities has been extracted to a library to allow
external tools to implement the kernel consumer functions.
Kconsumerd is now a daemon using the library, everything works as
before for this particular case.

Signed-off-by: Julien Desfossez <julien.desfossez@polymtl.ca>
Signed-off-by: David Goulet <david.goulet@polymtl.ca>