usermanager types refactoring

Relocating usermanager-specific API param types. We want to introduce a UserInfo type for login API purposes which conflicts with a usermanager-specific structure with the same name but different purpose.

Relocating the type to the apiserver subpackage to keep the type out of a common ever-growing state/api/params package.
move this down, the order is

stdlib imports

packages outside this repo

packages in this repo