dm vdo: add administrative state and action manager

This patch adds the admin_state structures which are used to track the
states of individual vdo components for handling of operations like suspend
and resume. It also adds the action manager which is used to schedule and
manage cross-thread administrative and internal operations.

Co-developed-by: J. corwin Coburn <corwin@hurlbutnet.net>
Signed-off-by: J. corwin Coburn <corwin@hurlbutnet.net>
Signed-off-by: Matthew Sakai <msakai@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>