[Feature] Add auto close to Toast component

[kuchaguangjie]

Summary

It can be closed by click close icon now.
Wondering is it possible to provide an optional timeout (e.g 5 seconds) after which the <Toast> will auto close.

Basic example

Like this one: https://sveltematerialui.com/demo/snackbar/
It can pop-out for default 5 seconds, or close by click the close icon.

[kuchaguangjie]

Or, is there an existing component for this?
I've checked <alert>, <toast>, <modal>, <tooltip>, seems <toast> is the closest one.

[kuchaguangjie]

Or, at least export the visible property, or a close() method, to let user close in other ways.

[jjagielka]

I was thinking of adding setTimeout default implementation, but decided not to as it would be too specific and it's easy to do by user.

Exporting visible should do the trick though.

[shinokada]

Can we add an example for users?

[jjagielka]

Sure. Will do.

[shinokada]

Thanks to @jjagielka .
#178
Added the feature to commit #2127151550a778d35bee5eb3b2b77f38423f50e4
I will update the version soon.