fix(fail_on): Added fail_on list to enable failing plan on condition such as decreasing partition count

[dbmurphy]

When using the provider, we found we wanted to fail plans if the partition count was reduced rather than trigger ForceNew. To support this but let others choose to replace the resource, we added fail_on, a list of string conditions. The code can check for these to override behaviors, which you can pass in when starting the provider to feature flag this change.