Fixed issue in future :class:`_future.Engine` where calling upon
:meth:`_future.Engine.begin` and entering the context manager would not
close the connection if the actual BEGIN operation failed for some reason,
such as an event handler raising an exception; this use case failed to be
tested for the future version of the engine. Note that the "future" context
managers which handle ``begin()`` blocks in Core and ORM don't actually run
the "BEGIN" operation until the context managers are actually entered. This
is different from the legacy version which runs the "BEGIN" operation up
front.

Fixes: #7272
Change-Id: I9667ac0861a9e007c4b3dfcf0fcf0829038a8711

Removed the previously deprecated ``case_sensitive`` parameter from
:func:`_sa.create_engine`, which would impact only the lookup of string
column names in Core-only result set rows; it had no effect on the behavior
of the ORM. The effective behavior of what ``case_sensitive`` refers
towards remains at its default value of ``True``, meaning that string names
looked up in ``row._mapping`` will match case-sensitively, just like any
other Python mapping.

Change-Id: I0dc4be3fac37d30202b1603db26fa10a110b618d

in order to remove LegacyRow / LegacyResult, we have
to also lose close_with_result, which connectionless
execution relies upon.

also includes a new profiles.txt file that's all against
py310, as that's what CI is on now.  some result counts
changed by one function call which was enough to fail the
low-count result tests.

Replaces Connectable as the common interface between
Connection and Engine with EngineEventsTarget.  Engine
is no longer Connectable.  Connection and MockConnection
still are.

References: #7257
Change-Id: Iad5eba0313836d347e65490349a22b061356896a

Fixes: #7258
Change-Id: I3577f665eca04f2632b69bcb090f0a4ec9271db9

In order to do LegacyRow we have to do Connection, which means
we lose close_with_result (hooray) which then means we
have to get rid of ORM session autocommit which relies on it, so
let's do that first.

Change-Id: I115f614733b1d0ba19f320ffa9a49f0d762db094

Adapted from 55e64f857daeb6057b85ff67297a774b when we
previously started a 2.0 branch.

Change-Id: Ib5af75df94b23104eebe0e918adcf979d798ea3b

this is the last warning to remove.

Also fixes some mistakes I made with the new
Base20DeprecationWarning and LegacyAPIWarning classes created,
where functions in deprecations.py were still hardcoded to
RemovedIn20Warning.

Change-Id: I9a6045ac9b813fd2f9668c4bc518c46a7774c6ef