restore parameter escaping for public methods

restore parameter escaping for public methods

Adjusted the fix made for :ticket:`8056` which adjusted the escaping of
bound parameter names with special characters such that the escaped names
were translated after the SQL compilation step, which broke a published
recipe on the FAQ illustrating how to merge parameter names into the string
output of a compiled SQL string. The change restores the escaped names that
come from ``compiled.params`` and adds a conditional parameter to
:meth:`.SQLCompiler.construct_params` named ``escape_names`` that defaults
to ``True``, restoring the old behavior by default.

Fixes: #8113
Change-Id: I9cbedb1080bc06d51f287fd2cbf26aaab1c74653