[vm/ffi] Native asset dynamic libraries should be dlclosed on isolate (group) shutdown #55521
Description
We have an open issue for caching:
When we address caching, we should cache per isolate group, so that we can dlclose (decreasing the ref count) per isolate group.
N.b. We need to make sure that multiple isolates racing for the same memoizable idempotent call only dlopen once to not get lost in the refcount.