fix: ensure dynamic fetches are tracked correctly (#66349)
This modifies the patched fetch implementation to better handle when
called within an `unstable_cache` callback. In these callbacks, it
should not throw an error related to dynamic access.
This replaces the verbose `trackDynamicFetch` instead with
`markCurrentScopeAsDynamic` which already has support for checking if
inside an unstable cache context. It also has been adjusted to be a
no-op when `export const dynamic = "force-static"`, further simplifying
the code within the patch fetch implementation.
