[c-c create] make post-create step optional (closes #2712041)
In this context the "post-create" step refers to the database's creation and
initialization. We want to be able to create a new instance but skip the
database creation (`db-create` and `db-init` commands) in automatic setup.
[cwconfig] Add optional configuration param to load a UI cube before other cubes
Needed later on to load UI cubes such as legacyui, and one day squareui.