Additional options bag in v() that supports explicit props and attrs

[matt-gadd]

We should consider supporting an optional explicit options bag in addition to our current properties object to v. This would allow users to target attributes or properties manually, which is potentially preferable in some custom element authoring situations. This probably means a change in maquette also.

[kitsonk]

Removing a discussion label because this is something we should do. Moving to beta5.

[kitsonk]

There has been some discussion that we are widened out and be a more broader breaking API change.