Add a lint rule forbidding use of "each()"
Ref T13588. "each()" has been a bad idea for a long time, and was formally deprecated in PHP 7.2 and removed in PHP 8.0.
Catch use of "each()" in lint and reject it.
Added and ran unit tests.
Maniphest Tasks: T13588
Differential Revision: https://secure.phabricator.com/D21741