Add the onvisible event handler to Element (#2911)

* Add the `onvisible` event using the IntersectionObserver

* Add a visible example

This example is based on https://codepen.io/ryanfinni/pen/VwZeGxN

* Remove web-sys CustomEvent feature for html package

* update js bindings and hash

* Use dioxus doc instead of lorem ipsum

* Fix clippy warning

* Add get_target method to the event data

* Make `get_time` return an Instant instead of a f64

* fix merge conflicts, compilinga

* remove target

* small nits

* serialzie as time_ms

* fix timing, works on desktop

* remove latent nits, fix hash

* box size clippy

* fix browserlist cargo.lock

---------

Co-authored-by: Evan Almloff <evanalmloff@gmail.com>
Co-authored-by: Jonathan Kelley <jkelleyrtp@gmail.com>

examples/clock.rs

@@ -1,5 +1,4 @@
 //! A simple little clock that updates the time every few milliseconds.
-//!
 
 use async_std::task::sleep;
 use dioxus::prelude::*;