Script templates for supporting replication

[justinneff]

For objects replicated databases, the objects (view, procedures, functions) cannot be dropped and recreated, but instead must only be altered. This creates a problem with our default script templates.

• Have a flag that can be set in the migration.yaml and during init that turns on replication support
• When replication support is turned on, have a set of templates that:
  • If the object does not exist, create a stub version of the object
  • Then as an ALTER object script instead of the CREATE object script