Setting ovn-monitor-all to 'true' will configure
ovn-controller to monitor all OVS database records
unconditionally. That will release some CPU resource
from OVS Southbound DB but will increase number of events
coming to ovn-controller.

Default value is 'false'.

Change-Id: I291e166013d8c88f00e84ceaf308251c352c9a79

Regularly, we experience issues in Kolla Ansible deployments because we
use wrong options in OpenStack configuration files. This is because
OpenStack services ignore unknown options. We also need to keep on top
of deprecated options that may be removed in the future. Integrating
oslo-config-validator into Kolla Ansible will greatly help.

Adds a shared role to run oslo-config-validator on each service. Takes
into account that services have multiple containers, and these may also
use multiple config files. Service roles are extended to use this shared
role. Executed with the new command ``kolla-ansible validate-config``.

Change-Id: Ic10b410fc115646d96d2ce39d9618e7c46cb3fbc

Instead of handling everything in one role - let's have small
fit-for-purpose roles, because in reality these are two hosts
roles and performance should be better with this approach.

[1]: https://docs.ovn.org/en/latest/intro/install/ovn-upgrades.html

Change-Id: I8f9dbe9d950323f16375ad5e1dbaedfb1be6585f