fix(multi-select): non-filterable MultiSelect should dispatch a blur event (#1080)

The non-filterable `MultiSelect` is missing a `blur` event.

Implementation-wise, we have to dispatch it and include the event as the `detail`. Otherwise, the filterable variant will dispatch "blur" twice because it has both a button and input.

The filterable `MultiSelect` continues to forward the blur event to the input.

src/MultiSelect/MultiSelect.svelte

@@ -1,4 +1,8 @@
 <script>
+  /**
+   * @event {FocusEvent | CustomEvent<FocusEvent>} blur
+   */
+
   /**
    * @typedef {any} MultiSelectItemId
    * @typedef {string} MultiSelectItemText
@@ -337,6 +341,9 @@
           if (inputRef) inputRef.focus();
         }
       }}"
+      on:blur="{(e) => {
+        if (!filterable) dispatch('blur', e);
+      }}"
       id="{id}"
       disabled="{disabled}"
       translateWithId="{translateWithId}"