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>

</details>
After:
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