LinkPropsBuilder should have onload event attribute

[emilbonnek]

Feature Request

Basically just the title. document::Link should probably have an onload event attribute we can use, similar to how buttons have an onclick etc.

I came across this when trying to use Shoelace in my Dioxus project.

Their section on setting up light and dark mode has this markup:

<link
  rel="stylesheet"
  media="(prefers-color-scheme:dark)"
  href="https://cdn.jsdelivr.net/npm/@shoelace-style/shoelace@2.20.0/cdn/themes/dark.css"
  onload="document.documentElement.classList.add('sl-theme-dark');"
/>

I am aware of the workarounds I can use, but I think it should be as straightforward as possible to translate simple things like this into Dioxus code.