switch any-point:coarse to pointer:coarse (#2631)

The current CSS keeps the hide cell buttons always on when Pluto is opened on laptops which also have a touchscreen.

Using pointer instead of any-pointer should only make the button always on only on devices that have the touchscreen as primary.

frontend/editor.css

@@ -1520,7 +1520,7 @@ pluto-input > button > span {
     }
 }
 
-@media screen and (any-pointer: coarse) {
+@media screen and (pointer: coarse) {
     pluto-cell > button,
     pluto-cell > pluto-runarea {
         opacity: 0;