feat(views): (de)hydration of views.

Dehydrated views are views that are structurally fixed, but their
directive instances are purged and are not being dirty-checked.

During the hydration of a view, the context for watched expressions is set
(allowing for local bindings.)
`hostElementInjector` most likely will be moved in another PR (added TODO). `inPlace` is needed for bootstrapping, but there is a possibility to change bootstrapping mechanism not to use the fake root proto view.