Support legacy select(<iterable>) in addition to select(<list>) in v1.4

Support legacy select(<iterable>) in addition to select(<list>) in v1.4

Fixed regression where use of an arbitrary iterable with the
:func:`_sql.select` function was not working, outside of plain lists. The
forwards/backwards compatibility logic here now checks for a wider range of
incoming "iterable" types including that a ``.c`` collection from a
selectable can be passed directly. Pull request compliments of Oliver Rice.

Fixes: #5935
Closes: #5936
Pull-request: https://github.com/sqlalchemy/sqlalchemy/pull/5936
Pull-request-sha: 575ab3e7df30fc8da03752d102c8eeb6cb3a3e3d

Change-Id: Icd972f1078d9ea96c47a64133079f00d9b0a66f3