[1.9] Create default_automation_condition_sensor in Definitions object

[OwenKephart]

Summary & Motivation

This shifts us to creating the default automation condition sensor in user-code land, which has the benefit of allowing us to update default values in sync with user-code updates, rather than host process version updates (particularly in a cloud context, these may be out of sync with each other).

However, in order to retain compatibility for users on a pre-1.9 version, we need to also keep the external data version as a fallback, in case their repository definition hasn't been generated using the latest code.

To support both use cases, I factored out the logic into a helper function.

How I Tested These Changes

Existing tests exercise these codepaths pretty heavily in a variety of oddball situations.

Changelog

NOCHANGELOG