cl-types: The big renaming to "derived types"

cl-types: The big renaming to "derived types"

`cl-defstruct` also defines a type and is also in CL, so
"cl-type" is not precise enough to talk about those types
defined with `cl-deftype`.  Use the term "derived type" to be
more clear, as is done in the HyperSpec.

* doc/misc/cl.texi (Derived types): Move `cl-deftype` to this
new subsection.  Document the use of derived types as method specializers.

* lisp/emacs-lisp/cl-extra.el (cl--types-of-memo): Rename from
`cl--type-unique`.
(cl--derived-type-dispatch-list): Rename from `cl--type-dispatch-list`.
(cl--derived-type-generalizer): Rename from `cl--type-generalizer`.
(cl--derived-type-generalizers): Rename from `cl--type-generalizers`.

* lisp/emacs-lisp/cl-lib.el (cl-generic-generalizers) <derived-types>:
Rename from <cl-types-of>.  Catch but don't hide errors when a derived
type cannot be used as an atomic type specifier.

* lisp/emacs-lisp/cl-preloaded.el (cl--derived-type-list): Rename from
`cl--type-list`.
(cl-derived-type-class): Rename from `cl-type-class`.
(cl--derived-type-class-make): Rename from `cl--type-class-make`.
(cl--define-derived-type): Rename from `cl--type-deftype`.

(cherry picked from commit b13044dae3db9c449a93f52fecfd848a3e7dd67d)