Add support for mark failed|default|required to host.v1/host.v2

[plorenz]

Add support for mark failed|default|required to host.v1/host.v2.

We currently mark healthy/unhealthy. This was setup so that it would remember the old state when it went unhealthy and could be restored to that original state when going back to healthy. However, in some cases, we want to be able to control the precedence directly, and that should be supported.