[v6] Add generic to useLocation

[SevenOutman]

It seems that history.Location itself need to be improved too.

// No
type State = object | null;

interface Location<S extends State = State> {
  state: S;
}

// Yes
interface Location<S extends object = object> {
  state: S | null;
}

[timdorr]

#7326 (comment)