`UseStateHandle` does not implement `PartialEq` so can't be used as a prop field

[mc1098]

Problem

Steps To Reproduce
Steps to reproduce the behavior:
Try to use UseStateHandle<T> as a field in a Properties struct - regardless of whether T: PartialEq it will complain that UseStateHandle doesn't implement PartialEq.

Expected behavior
At minimum if T: PartialEq then so should UseStateHandle<T>, however I think we could implement PartialEq even
when T is not PartialEq.

Environment:

• Yew version: master

[ranile]

This also applies to UseReducerHandle. I'll PR a PartialEq impl for both of them