[dynamicIO] warn for disallowed dynamic in dev (#71526)
Previously our rules for allowed dynamic were only enforced in builds.
This is not tenable for serious adoption because you can't spend all day
working on your site and then find out its broken when you build /
deploy.
To address this I've added a simulated prerendering during dev that
should enforce the same rules for rendered routes in dev that would
apply during a build. There is no way to avoid doing additional work to
implement this feature because we need the abort mechanism of SSR to
actually find the dynamic holes that should be disallowed. I was able to
avoid completely duplicating the RSC render however by capturing the
stream chunks available before the first task completes and stashing
them away as a simulated halted RSC payload.
I did have to introduce prospective renders to the RSC render and the
validating SSR render however to work around issues of lazy module
initialization where functions like Math.random and new Date() in module
scope would incorrectly trigger dynamic validation when you would not
expect them to.
