menu: just have an empty space for checked menuitems (#2785)

### Change Type

- [x] `patch` — Bug fix

- UI: Update menu checkbox style.

assets/icons/icon/checkbox-empty.svg

@@ -1,8 +1,8 @@
 <?xml version="1.0" encoding="UTF-8" standalone="no"?>
 <svg
-   width="30"
-   height="30"
-   viewBox="0 0 30 30"
+   width="24"
+   height="24"
+   viewBox="0 0 24 24"
    fill="none"
    version="1.1"
    id="svg1"
@@ -10,10 +10,4 @@
    xmlns:svg="http://www.w3.org/2000/svg">
   <defs
      id="defs1" />
-  <path
-     d="M 6.4651362,4.9397125 H 23.974196 a 1.7194619,1.7194619 45 0 1 1.719462,1.7194619 l 0,17.5090556 a 1.779661,1.779661 135 0 1 -1.779661,1.779661 H 6.5922549 A 1.9067797,1.9067797 45 0 1 4.6854752,24.041111 V 6.7193735 a 1.779661,1.779661 135 0 1 1.779661,-1.779661 z"
-     stroke="#000000"
-     stroke-width="3"
-     id="path1"
-     transform="translate(0.81043485,0.55619755)" />
 </svg>