Renege on anonymous &rest (bug#50268, bug#50720)

Renege on anonymous &rest (bug#50268, bug#50720)

Allowing &rest without a variable name following turned out not to be
very useful, and it never worked properly.  Disallow it.

* lisp/emacs-lisp/bytecomp.el (byte-compile-check-lambda-list):
* src/eval.c (funcall_lambda):
Signal error for &rest without variable name.
* doc/lispref/functions.texi (Argument List): Adjust manual.
* etc/NEWS (file): Announce.
* test/src/eval-tests.el (eval-tests--bugs-24912-and-24913):
Extend test, also checking with and without lexical binding.
(eval-tests-accept-empty-optional-rest): Reduce to...
(eval-tests-accept-empty-optional): ...this, again checking
with and without lexical binding.