Split import into var and type to avoid breaking backword compatability of tsserverlibrary - #16409

This works as a quick fix but I think this should be filed as a bug?
Given:

namespace N {
    export const enum E { A, B }
}
namespace M {
    export import E = N.E;
}

I think we should emit something inside M if --preserveConstEnums is on.

We already do that in this case:
a.ts

export const enum E { A, B }

b.ts

export { E } from "./a";

we have treated --preserveConstEnums as a debugging flag, it does not change the emitted code, it jsut does not erase the enum declaration, so that at debug time you can look at the reverse map.

we have overloaded that use in the services and the compiler. i wounder if what we need is a flag to inline regular enum values instead.