feat: add image support for social media (#96)

页脚社交媒体支持图片类型。

/kind feature

<img width="592" alt="image" src="https://github.com/halo-dev/theme-earth/assets/21301288/7bf77f2c-125d-4243-b38c-0e340b82df64">
<img width="1403" alt="image" src="https://github.com/halo-dev/theme-earth/assets/21301288/67c2c232-1130-4d4f-ae13-7b3f39af8c79">

Fixes #92 

```release-note
页脚社交媒体支持图片类型。
```

templates/modules/footer.html

@@ -28,18 +28,7 @@
       </ul>
     </th:block>
 
-    <th:block th:with="social_medias = ${theme.config.footer.social_media}">
-      <div th:unless="${#lists.isEmpty(social_medias)}" class="mt-4 flex space-x-6 sm:mt-0 sm:justify-center">
-        <a
-          th:each="social_media : ${social_medias}"
-          th:href="${social_media.url}"
-          class="text-gray-500 hover:text-gray-900 dark:hover:text-white"
-          th:title="${social_media.name}"
-        >
-          <div th:classappend="${social_media.icon}" class="h-5 w-5"></div>
-        </a>
-      </div>
-    </th:block>
+    <th:block th:replace="~{modules/footer-social}" />
   </div>
   <hr class="my-6 border-gray-100 dark:border-slate-700 sm:mx-auto lg:my-8" />
   <div class="space-y-1">
@@ -163,18 +152,7 @@
         <halo:footer />
       </p>
     </div>
-    <div
-      th:with="social_medias = ${theme.config.footer.social_media}"
-      class="mt-4 flex justify-center space-x-6 sm:mt-0"
-    >
-      <a
-        th:each="social_media : ${social_medias}"
-        th:href="${social_media.url}"
-        class="text-gray-500 hover:text-gray-900 dark:hover:text-white"
-        th:title="${social_media.name}"
-      >
-        <div th:classappend="${social_media.icon}" class="h-5 w-5"></div>
-      </a>
-    </div>
+
+    <th:block th:replace="~{modules/footer-social}" />
   </div>
 </footer>