feat: Add magik support

Author: jcs090218

indent-control.el

@@ -99,6 +99,7 @@
     (lisp-interaction-mode . 2)
     (livescript-mode       . 2)
     (lua-mode              . 4)
+    (magik-mode            . 4)
     (matlab-mode           . 4)
     (meson-mode            . 2)
     (mips-mode             . 4)
@@ -208,6 +209,7 @@
     (lisp-interaction-mode . lisp-body-indent)
     (livescript-mode       . livescript-tab-width)
     (lua-mode              . lua-indent-level)
+    (magik-mode            . magik-indent-level)
     (matlab-mode           . matlab-indent-level)
     (meson-mode            . meson-indent-basic)
     (mips-mode             . mips-tab-width)