from_iter on heapless::String should be generic over any iterator that yields a type that implements AsRef<str>

You currently cannot use from_iter directly with a &[CompactString] for example. You have to do .into_iter().map(...) which is annoying. I ended up building my own helper function for this but it would be nicer if the heapless crate itself provided this generic impl.

This is my helper function:

pub fn build_hstring<const N: usize, I, S>(iter: I) -> heapless::String<N>
where
    I: IntoIterator<Item = S>,
    S: AsRef<str>,
{
    let mut new = heapless::String::<N>::new();
    for c in iter {
        new.push_str(c.as_ref()).expect("build_hstring: capacity exceeded");
    }
    new
}

Start from heapless::String::from_iter and compare it with the helper shown in the issue, including its IntoIterator and AsRef bounds. Confirm the desired behavior with an iterator over string-like values such as &[CompactString]; it is done when callers no longer need an intermediate map to build a heapless::String.