filesystem: Add process file type for containers
filesystem: Add process file type for containers

Add a new type of file to be stored locally. That way, virtcontainers can
provide needed information about container's process accross different
API calls.

Signed-off-by: Sebastien Boeuf <90b401417360b1924ef3f520ddee932686110f85@intel.com>

wcwxyz/virtcontainers,wcwxyz/virtcontainers,containers/virtcontainers,wcwxyz/virtcontainers,containers/virtcontainers