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 issue is not present in the
2.0 series which uses a different reflection architecture. Test support is
added to ensure ``has_table()`` remains working per spec re: views.

Fixes: #8700
Change-Id: I119a91ec07911edb08cf0799234827fec9ea1195