fix: Update invalid type imports (cibernox#1589)

Copied from cibernox#1577

For consumers that end up importing this file, the type declarations
don't include `/addon`

`/addon` ends up working during development time, because the original
source is in TS -- but it ends up not being the same as the emitted
declarations.

addon/components/power-select.ts

@@ -20,7 +20,7 @@ import {
 } from '../utils/group-utils';
 // @ts-ignore
 import { restartableTask, timeout } from 'ember-concurrency';
-import { Dropdown, DropdownActions } from 'ember-basic-dropdown/addon/components/basic-dropdown';
+import type { Dropdown, DropdownActions } from 'ember-basic-dropdown/components/basic-dropdown';
 
 interface SelectActions extends DropdownActions {
   search: (term: string) => void

components/power-select.d.ts

@@ -1,6 +1,6 @@
 import Component from '@glimmer/component';
 import { MatcherFn } from '../utils/group-utils';
-import { Dropdown, DropdownActions } from 'ember-basic-dropdown/addon/components/basic-dropdown';
+import type { Dropdown, DropdownActions } from 'ember-basic-dropdown/components/basic-dropdown';
 interface SelectActions extends DropdownActions {
     search: (term: string) => void;
     highlight: (option: any) => void;