* Edebug: Generalize `&lookup`, use it for `cl-macrolet` and `cl-generic`

* Edebug: Generalize `&lookup`, use it for `cl-macrolet` and `cl-generic`

This allows the use of (declare (debug ...)) in the lexical macros
defined with `cl-macrolet`.  It also fixes the names used by Edebug
for the methods of `cl-generic` so it doesn't need to use gensym
and so they don't include the formal arg names any more.

* lisp/emacs-lisp/edebug.el (edebug--match-&-spec-op):
Rename from `edebug--handle-&-spec-op`.
(edebug--match-&-spec-op <&interpose>): Rename from `&lookup` and
generalize so it can let-bind dynamic variables around the rest of the parse.
(edebug-lexical-macro-ctx): Rename from `edebug--cl-macrolet-defs` and
make it into an alist.
(edebug-list-form-args): Use the specs from `edebug-lexical-macro-ctx`
when available.
(edebug--current-cl-macrolet-defs): Delete var.
(edebug-match-cl-macrolet-expr, edebug-match-cl-macrolet-name)
(edebug-match-cl-macrolet-body): Delete functions.
(def-declarations): Use new `&interpose`.
(edebug--match-declare-arg): Rename from `edebug--get-declare-spec` and
adjust to new calling convention.

* lisp/subr.el (def-edebug-elem-spec): Fix docstring.
(eval-after-load): Use `declare`.

* lisp/emacs-lisp/cl-generic.el: Fix Edebug names so we don't need
gensym any more and we only include the specializers but not the formal
arg names.
(cl--generic-edebug-name): New var.
(cl--generic-edebug-remember-name, cl--generic-edebug-make-name): New funs.
(cl-defgeneric, cl-defmethod): Use them.

* lisp/emacs-lisp/cl-macs.el: Add support for `debug` declarations in
`cl-macrolet`.
(cl-declarations-or-string):
Fix use of `lambda-doc` and allow use of `declare`.
(edebug-lexical-macro-ctx): Declare var.
(cl--edebug-macrolet-interposer): New function.
(cl-macrolet): Use it to pass the right `lexical-macro-ctx` to the body.

* lisp/emacs-lisp/pcase.el (pcase-PAT): Use new `&interpose`.
(pcase--edebug-match-pat-args): Rename from `pcase--get-edebug-spec` and
adjust to new calling convention.

* test/lisp/emacs-lisp/cl-generic-tests.el (cl-defgeneric/edebug/method):
Adjust to the new names.

* test/lisp/emacs-lisp/edebug-tests.el (edebug-cl-defmethod-qualifier)
(edebug-tests-cl-flet): Adjust to the new names.

* doc/lispref/edebug.texi (Specification List): Document &interpose.