[Perf] Do not hydrate static elements

[nolanlawson]

Marko has an optimization where, for components that are fully static, the following happens:

1. The components are SSR'ed, but
2. The components are not hydrated/CSR'ed

We already have the ability in the server to detect static fragments, so we should be able to do a similar optimization.

Even better would be to skip hydration at a fragment (not component) level, but this may be trickier.