Support sqlalchemy 1.4 exec_driver_sql, text() for strings

Support sqlalchemy 1.4 exec_driver_sql, text() for strings

Adjusted tests so that only connection-explicit execution
is used, along with the use of text() for string invocation.
Tests that are testing explicitly for deprecation warnings
will bypass SQLAlchemy warnings.   Added the RemovedIn20 warning
as an error raise for these two specific deprecation cases.

Co-authored-by: Mike Bayer <mike_mp@zzzcomputing.com>
Change-Id: I4f6b83366329aa95204522c9e99129021d1899fc