Change: Enterprise HA policy cleanup

Ref: https://dev.cfengine.com/issues/6813

The CFEngine Enterpise HA policy uses features from 3.6. When the policy is
loaded on 3.5 and earlier clients it fails to validate.

Make the HA policy only load on En Additionally there is no reason to load the
HA policy on clients that are not enterprise hubs.

Change class names to make them more self describing and specific to reduce
changes of clashing with custom policies.

Move enablement of hub ha to def and update_def from ha_def with other feature
enablement classes.
This is not working. While executing agent I can see following stuff:
"error Bundle 'ha_def' listed in the bundlesequence is not a defined bundle", "error Bundle 'ha_main' listed in the bundlesequence is not a defined bundle".
My best guess is that while inputs are created 'cfengine_enterprise' bundle is evaluated but here 'enable_cfengine_enterprise_hub_ha' class might be (and actually is) not set so 'cfengine_enterprise.inputs' is empty list. 
This seems to be some circular dependency and special evaluation of bundlesequence and inputs in body common control.