I guess there could be enough people liking to make the Settings menu
item right aligned. As a site admin, I found it's easier to find the
right-aligned Settings menu item.
Tested with various sizes:



There is a small layout shift in when active tab changes. Notice how the
actions SVG is unstable:

This is because the active item with bold text is wider then the
inactive one. I have applied [this
trick](https://stackoverflow.com/a/32570813/808699) to prevent this
layout shift. It's only active inside `<overflow-menu>` because I wanted
to avoid changing HTML and doing it in regular JS would cause a flicker.
I don't expect us to introduce other similar menus without
`<overflow-menu>`, so that place is likely fine.

I also changed the weight from 500 to 600, slightly reduced horizontal
padding, merged some tab-bar related CSS rules and a added a small
margin below repo-header so it does not look so crammed against the
buttons on top.
---------
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
1. Add `<overflow-menu>` web component
2. Rename `<gitea-origin-url>` to `<origin-url>` and make filenames
match.
<img width="439" alt="image"
src="2fbe4ca4-110b-4ad2-8e17-c1e116ccbd74">
<img width="444" alt="Screenshot 2024-03-02 at 21 36 52"
src="aa8f786e-dc8c-4030-b12d-7cfb74bdfd6e">
<img width="537" alt="Screenshot 2024-03-03 at 03 05 06"
src="fddd50aa-adf1-4b4b-bd7f-caf30c7b2245">


TODO:
- [x] Check if removal of `requestAnimationFrame` is possible to avoid
flash of content. Likely needs a `MutationObserver`.
- [x] Hide tippy when button is removed from DOM.
- [x] ~~Implement right-aligned items
(https://github.com/go-gitea/gitea/pull/28976)~~. Not going to do it.
- [x] Clean up CSS so base element has no background and add background
via tailwind instead.
- [x] Use it for org and user page.
---------
Co-authored-by: Giteabot <teabot@gitea.io>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>