Add dom.first! and dom.all! support to all selector framework plugins

[briancavalier]

It seems like we end up writing this a lot, and the most common use case is probably fetching the first match

{ $ref: 'dom.query!.whatever', i:0 }

So let's add dom.first! that automatically resolves to the first match, rather than to a nodelist of 1 item. It can take advantage of any selector-specific optimizations, such as :first, too.

As a nice parallel, let's add dom.all! which will be a synonym for dom.query! ... and maybe we should deprecate dom.query!

[briancavalier]

dom.all! and dom.first! now implemented in all dom plugins, even wire/dom, which will use querySelectorAll if available.