Add type awareness to evaluator

Add type awareness to evaluator

Fixed regression where using ORM update() with synchronize_session='fetch'
would fail due to the use of evaluators that are now used to determine the
in-Python value for expressions in the the SET clause when refreshing
objects; if the evaluators make use of math operators against non-numeric
values such as PostgreSQL JSONB, the non-evaluable condition would fail to
be detected correctly. The evaluator now limits the use of math mutation
operators to numeric types only, with the exception of "+" that continues
to work for strings as well. SQLAlchemy 2.0 may alter this further by
fetching the SET values completely rather than using evaluation.

Fixes: #8507
Change-Id: Icf7120ccbf4266499df6bb3e05159c9f50971d69