refactor(frontend): 空/エラー結果表示をコンポーネント化 (#15963)

* wip

* wip

* wip

* wip

* wip

* Update MkResult.vue

* Add storybook story for MkResult (#15964)

* Update MkResult.vue

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Co-authored-by: taichan <40626578+tai-cha@users.noreply.github.com>

packages/frontend/src/widgets/WidgetRss.vue

@@ -11,10 +11,7 @@ SPDX-License-Identifier: AGPL-3.0-only
 
 	<div class="ekmkgxbj">
 		<MkLoading v-if="fetching"/>
-		<div v-else-if="(!items || items.length === 0) && widgetProps.showHeader" class="_fullinfo">
-			<img :src="infoImageUrl" draggable="false"/>
-			<div>{{ i18n.ts.nothing }}</div>
-		</div>
+		<MkResult v-else-if="(!items || items.length === 0) && widgetProps.showHeader" type="empty"/>
 		<div v-else :class="$style.feed">
 			<a v-for="item in items" :key="item.link" :class="$style.item" :href="item.link" rel="nofollow noopener" target="_blank" :title="item.title">{{ item.title }}</a>
 		</div>
@@ -32,7 +29,6 @@ import type { WidgetComponentEmits, WidgetComponentExpose, WidgetComponentProps
 import type { GetFormResultType } from '@/utility/form.js';
 import MkContainer from '@/components/MkContainer.vue';
 import { i18n } from '@/i18n.js';
-import { infoImageUrl } from '@/instance.js';
 
 const name = 'rss';