test support for has_table()->view; backport to 1.4

test support for has_table()->view; backport to 1.4

For 1.4 only; in 2.0 this just refines the test suite a bit.

Fixed regression which occurred throughout the 1.4 series where the
:meth:`.Inspector.has_table` method, which historically reported on views
as well, stopped working for SQL Server.  The method never worked for
Oracle in this way, so for compatibility within the 1.4 series,
Oracle's dialect remains returning False for ``has_table()`` against a
view within the 1.4 series.

The issue is not present in the 2.0 series which uses a different
reflection architecture, where has_table() reports True for views on all
backends including SQL Server and Oracle. Test support is added within the
1.4 series to ensure ``has_table()`` remains working per spec re: views.

Fixes: #8700
Change-Id: I119a91ec07911edb08cf0799234827fec9ea1195
(cherry picked from commit c02f6b744d304578fe67da2e13d2c02ab71140d2)