[SSR] Make dynamic import()s no-ops

[nolanlawson]

In the SSR compiler, dynamic import()s should (probably) be no-ops because we run in sync mode so you wouldn't be able to do anything with the constructor you import anyway.

We also need to strip these import()s anyway because core will complain if it sees them after compilation.

[git2gus]

This issue has been linked to a new work item: W-17248485

[wjhsf]

If we're moving forward with sync mode, do we need to block more flavors of async operations?

[nolanlawson]

No, they just won't work. We already have a test for Promise.resolve().