Unify generation between Core and ORM query

Unify generation between Core and ORM query

generation is to be enhanced to include caching
functionality, so ensure that Query and all generative in Core
(e.g. select, DML etc) are using the same generations system.

Additionally, deprecate Select.append methods and state
Select methods independently of their append versions.
Mutability of expression objects is a special case only when
generating new objects during a visit.

Fixes: #4637
Change-Id: I3dfac00d5e0f710c833b236f7a0913e1ca24dde4