Allow use of for loops with `for .. in .. { ... }` syntax in `html!`

Describe the feature you'd like
Allow using for loops like:

html! {
    for val in range {
      <p> { val } </p>
    }
}

Is your feature request related to a problem? Please describe. (Optional)
Current solutions hurt readability when used inside deeply nested html and imo, aren't that concise.

Describe alternatives you've considered (Optional)
There are two alternatives to this (mentioned here). Both of which require you to wrap them in html! or empty tags which doesn't read well.

Additional context (Optional)
This will also bring loop syntax inside html! in-line with the if statement synatx

Questionnaire

• I'm interested in implementing this myself but don't know where to start
• I would like to add this feature
• I don't have time to add this right now, but maybe later

Start with the html! syntax shown in the issue and read the linked Yew iterators documentation to understand the current alternatives. Define the parser and rendering behavior needed for the displayed for-loop form, then verify that equivalent nested HTML can use it without the existing wrapper patterns.