mon: osd crush rule functional tests

* A set of test for the simplest operations
* A test covering all cases of osd crush rule

Signed-off-by: Loic Dachary <loic@dachary.org>
mon: osd crush rule create-simple functional tests

Basic tests and a test that create the conditions where a paxos proposal
is pending and the rule is found to exist in the pending proposal.

Signed-off-by: Loic Dachary <loic@dachary.org>