reject methods as lambda SQL callables

reject methods as lambda SQL callables

Added an informative error message when a method object is passed to a SQL
construct. Previously, when such a callable were passed, as is a common
typographical error when dealing with method-chained SQL constructs, they
were interpreted as "lambda SQL" targets to be invoked at compilation time,
which would lead to silent failures. As this feature was not intended to be
used with methods, method objects are now rejected.

Fixes: #7032
Change-Id: If714715bd8c11557ab769ee3b1a24264b0b06acc