transient-infix-set(argument): Fix disabling incompatible options

When `argument' is unbound, fall back to `argument-format' instead of
`argument-regexp'.  The format can easily be used both as the matcher
and the match candidate, while the regexp is only suitable as matcher.

Fallback from `argument' to `argument-format', not only for the
argument that is being enabled, but also for the arguments that might
have to be disabled in response.

lisp/transient.el

@@ -3190,16 +3190,18 @@ prompt."
   (when-let* ((--- value)
               (arg (if (slot-boundp obj 'argument)
                        (oref obj argument)
-                     (oref obj argument-regexp)))
+                     (oref obj argument-format)))
               (spec (oref transient--prefix incompatible))
               (incomp (cl-mapcan (lambda (rule)
                                    (and (member arg rule)
                                         (remove arg rule)))
                                  spec)))
     (dolist (obj transient--suffixes)
-      (when (and (cl-typep obj 'transient-argument)
-                 (slot-boundp obj 'argument)
-                 (member (oref obj argument) incomp))
+      (when-let* ((--- (cl-typep obj 'transient-argument))
+                  (arg (if (slot-boundp obj 'argument)
+                           (oref obj argument)
+                         (oref obj argument-format)))
+                  (--- (member arg incomp)))
         (transient-infix-set obj nil)))))
 
 (cl-defgeneric transient-set-value (obj)