imagemagick: update pages (#12874)

* compare, convert, identify, import, mogrify, montage:
   move pages to subcommands of `magick`, create alias pages

* convert: add deprecation notice

---------

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/import.md

@@ -1,17 +1,7 @@
 # import
 
-> Capture some or all of an X server screen, and save the image to a file.
-> Part of ImageMagick.
-> More information: <https://imagemagick.org/script/import.php>.
+> This command is an alias of `magick import`.
 
-- Capture the entire X server screen into a PostScript file:
+- View documentation for the original command:
 
-`import -window root {{path/to/output.ps}}`
-
-- Capture contents of a remote X server screen into a PNG image:
-
-`import -window root -display {{remote_host}}:{{screen}}.{{display}} {{path/to/output.png}}`
-
-- Capture a specific window given its ID as displayed by `xwininfo` into a JPEG image:
-
-`import -window {{window_id}} {{path/to/output.jpg}}`
+`tldr magick import`