Support rectangular regions for more commands

Support rectangular regions for more commands

* lisp/simple.el (region-extract-function): Handle the arg value ‘bounds’.
(region-insert-function): New function.
(shell-command-on-region): Add arg ‘region-noncontiguous-p’.
If non-nil, operate on multiple chunks.
(region-noncontiguous-p): New function.

* lisp/rect.el: Add function rectangle--insert-region
around region-insert-function.
(extract-rectangle-bounds): New function.
(rectangle--extract-region): Handle the arg value ‘bounds’.
(rectangle--insert-region): New function.

* lisp/emulation/cua-rect.el: Add function cua--insert-rectangle
around region-insert-function.
(cua--extract-rectangle-bounds): New function.
(cua--rectangle-region-extract): Handle the arg value ‘bounds’.

* lisp/replace.el (query-replace, query-replace-regexp): Add arg
‘region-noncontiguous-p’.  Use ‘use-region-p’.
(query-replace-regexp-eval, map-query-replace-regexp)
(replace-string, replace-regexp): Use ‘use-region-p’.
(keep-lines, flush-lines, how-many): Use ‘use-region-p’.
(perform-replace): Add arg ‘region-noncontiguous-p’.
If non-nil, operate on multiple chunks.

* src/casefiddle.c (Fdowncase_region): Add arg ‘region-noncontiguous-p’.
If non-nil, operate on multiple chunks. (Bug#19829)