Fine tune more downdrop settings, use SVG for labels, improve Repo Topic Edit form (#23626)

Although it seems that some different purposes are mixed in this PR,
however, they are all related, and can be tested together, so I put them
together to save everyone's time.

Diff: `+79 −84`, everything becomes much better.

### Improve the dropdown settings.

Move all fomantic-init related code into our `fomantic.js`

Fine-tune some dropdown global settings, see the comments.

Also help to fix the first problem in #23625 , cc: @yp05327 

The "language" menu has been simplified, and it works with small-height
window better.

### Use SVG instead of `<i class="delete icon">`

It's also done by `$.fn.dropdown.settings.templates.label` , cc:
@silverwind

### Remove incorrect `tabable` CSS class

It doesn't have CSS styles, and it was only in Vue. So it's totally
unnecessary, remove it by the way.

### Improve the Repo Topic Edit form

* Simplify the code
* Add a "Cancel" button
* Align elements

Before:

<details>

![image](https://user-images.githubusercontent.com/2114189/223325782-f09532de-0c38-4742-ba86-ed35cc9a858d.png)

</details>

After:

![image](https://user-images.githubusercontent.com/2114189/226796347-207feb0a-b3cd-4820-8a3e-01930bab1069.png)

web_src/js/features/common-global.js

@@ -83,7 +83,7 @@ export function initGlobalCommon() {
   const $uiDropdowns = $('.ui.dropdown');
 
   // do not init "custom" dropdowns, "custom" dropdowns are managed by their own code.
-  $uiDropdowns.filter(':not(.custom)').dropdown({fullTextSearch: 'exact'});
+  $uiDropdowns.filter(':not(.custom)').dropdown();
 
   // The "jump" means this dropdown is mainly used for "menu" purpose,
   // clicking an item will jump to somewhere else or trigger an action/function.
@@ -111,14 +111,12 @@ export function initGlobalCommon() {
     },
   });
 
-  // special animations/popup-directions
-  $uiDropdowns.filter('.slide.up').dropdown({transition: 'slide up'});
-  $uiDropdowns.filter('.upward').dropdown({direction: 'upward'});
+  // special popup-directions
+  $uiDropdowns.filter('.upward').dropdown('setting', 'direction', 'upward');
 
   $('.ui.checkbox').checkbox();
 
   $('.tabular.menu .item').tab();
-  $('.tabable.menu .item').tab();
 
   $('.toggle.button').on('click', function () {
     toggleElem($($(this).data('target')));