Refactor hiding-methods, remove jQuery show/hide, remove `.hide` class, remove inline style=display:none (#22950)

Close #22847

This PR:

* introduce Gitea's own `showElem` and related functions
* remove jQuery show/hide
* remove .hide class
* remove inline style=display:none 

From now on:

do not use:
* "[hidden]" attribute: it's too weak, can not be applied to an element
with "display: flex"
* ".hidden" class: it has been polluted by Fomantic UI in many cases
* inline style="display: none": it's difficult to tweak
* jQuery's show/hide/toggle: it can not show/hide elements with
"display: xxx !important"

only use:
* this ".gt-hidden" class
* showElem/hideElem/toggleElem functions in "utils/dom.js"

cc: @silverwind , this is the all-in-one PR

1 files changed, 4 insertions, 3 deletions

diff --git a/web_src/js/features/imagediff.js b/web_src/js/features/imagediff.js
index 250ea95798..7a285f1f8d 100644
--- a/web_src/js/features/imagediff.js
+++ b/web_src/js/features/imagediff.js
@@ -1,4 +1,5 @@
 import $ from 'jquery';
+import {hideElem} from '../utils/dom.js';
 
 function getDefaultSvgBoundsIfUndefined(svgXml, src) {
   const DefaultSize = 300;
@@ -104,7 +105,7 @@ export function initImageDiff() {
               if (bounds) {
                 info.$image.attr('width', bounds.width);
                 info.$image.attr('height', bounds.height);
-                info.$boundsInfo.hide();
+                hideElem(info.$boundsInfo);
               }
             }
           }
@@ -128,8 +129,8 @@ export function initImageDiff() {
         initOverlay(createContext($imageAfter[2], $imageBefore[2]));
       }
 
-      $container.find('> .loader').hide();
-      $container.find('> .hide').removeClass('hide');
+      hideElem($container.find('> .loader'));
+      $container.find('> .gt-hidden').removeClass('gt-hidden');
     }
 
     function initSideBySide(sizes) {