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/magick-mogrify.md

@@ -0,0 +1,26 @@
+# magick mogrify
+
+> Perform operations on multiple images, such as resizing, cropping, flipping, and adding effects.
+> Changes are applied directly to the original file.
+> See also: `magick`.
+> More information: <https://imagemagick.org/script/mogrify.php>.
+
+- Resize all JPEG images in the directory to 50% of their initial size:
+
+`magick mogrify -resize {{50%}} {{*.jpg}}`
+
+- Resize all images starting with `DSC` to 800x600:
+
+`magick mogrify -resize {{800x600}} {{DSC*}}`
+
+- Convert all PNGs in the directory to JPEG:
+
+`magick mogrify -format {{jpg}} {{*.png}}`
+
+- Halve the saturation of all image files in the current directory:
+
+`magick mogrify -modulate {{100,50}} {{*}}`
+
+- Double the brightness of all image files in the current directory:
+
+`magick mogrify -modulate {{200}} {{*}}`