Remove clones from events passing

[filipdutescu]

Description

All events are currently sent to html! macro by cloning them. This is very inefficient and bad code.

Proposal

Swap all event callbacks from Option<yew::Callback<T>> to yew::Callback<T>, as the default (using #[prop_or_default]) does basically the same anyways (not setting an event on the element). This further allows passing by reference, ie onclick={&props.onclick}.

Other relevant information

No response