Add option to not re-focus ComboBox when invoking clear() (#1000)

* feat(combo-box): add option to clear accessor to not re-focus input

Closes #994

* yarn build:lib

* test(combo-box): validate clear accessor params

* docs(combo-box): add clear without focus to "Clear selection" example

types/ComboBox/ComboBox.svelte.d.ts

@@ -158,5 +158,5 @@ export default class ComboBox extends SvelteComponentTyped<
   /**
    * Clear the combo box programmatically
    */
-  clear: () => void;
+  clear: (options?: { focus?: boolean }) => void;
 }