NRPE check for compute which cannot authenticate with a mon

[Adam Dyess]

Please add a check for situations where the OSD cannot authenticate to the MON's API.

We had a situation where the ceph-osds running nautilus (and mimic) couldn't not auth with an octopus mon, but all OSDs were reported as "up".

this was spamming in each ceph-ods.log

```
auth: could not find secret_id=27008
cephx: verify_authorizer could not get service secret for service osd secret_id=27008
```

Another command which failed from the hypervisor was this
sudo ceph df --format=json --id nova-compute-kvm --conf /var/lib/charm/nova-compute-kvm/ceph.conf
[errno 13] error connecting to the cluster

Perhaps it could be used as the basis for the NRPE check