fix(combobox): fix import path for some bundlers (carbon-design-syste…

…m#11639)

### Related Ticket(s)

Closes carbon-design-system#11635

### Description

Adds the file extension to the import path for `lit/directives/if-defined.js` to fix issues with some bundlers.

### Changelog

**Changed**

- Adds the file extension to the import path for `lit/directives/if-defined.js` to fix issues with some bundlers.

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web-components/packages/carbon-web-components/src/components/combo-box/combo-box.ts

@@ -17,7 +17,7 @@ import CDSDropdown, { DROPDOWN_KEYBOARD_ACTION } from '../dropdown/dropdown';
 import CDSComboBoxItem from './combo-box-item';
 import styles from './combo-box.scss';
 import { carbonElement as customElement } from '../../globals/decorators/carbon-element';
-import { ifDefined } from 'lit/directives/if-defined';
+import { ifDefined } from 'lit/directives/if-defined.js';
 import ifNonEmpty from '../../globals/directives/if-non-empty';
 
 export { DROPDOWN_DIRECTION, DROPDOWN_SIZE } from '../dropdown/dropdown';