[v1] allow dev to specify extra attributes on the HTML element

[tabacitu]

If loading something from a CDN, the dev might want to pass integrity and crossorigin. Or hell, maybe even something for lazy-loading. Currently we have no way of doing that. So after #6 I think we should add a second parameter, so that you can do:

@loadOnce('http://domain.com/some.js', [
    'integrity' => 'sha256-0YPKAwZP7Mp3ALMRVB2i8GXeEndvCq3eSl/WsAl1Ryk=',
    'crossorigin' => 'anonymous',
])

It's not pretty, but... it should be useful. The implementation isn't difficult at all, it's basically the same thing we do in the script widget in Backpack. And this parameter would be optional, so it'd be a non-breaking change.

Just writing it out so we don't forget about it.

[promatik]

We can close this one since bassets allows to set tag attributes 🎉