feat: add download feature for attachment (#5496)

#### What type of PR is this?

/kind feature
/area ui
/milestone 2.14.0

#### What this PR does / why we need it:

附件支持下载。

<img width="471" alt="image" src="https://github.com/halo-dev/halo/assets/21301288/97909ef8-8117-4ea9-aa15-73295a1b7b01">


#### Which issue(s) this PR fixes:

Fixes https://github.com/halo-dev/halo/issues/5476

#### Special notes for your reviewer:

测试方式：

1. 上传若干附件。
2. 测试下载功能是否符合预期。

#### Does this PR introduce a user-facing change?

```release-note
为附件添加下载功能
```

ui/console-src/modules/contents/attachments/components/AttachmentListItem.vue

@@ -7,6 +7,7 @@ import {
   Toast,
   VDropdownItem,
   Dialog,
+  VDropdownDivider,
 } from "@halo-dev/components";
 import { computed, ref } from "vue";
 import type { Attachment } from "@halo-dev/api-client";
@@ -101,6 +102,29 @@ const { operationItems } = useOperationItemExtensionPoint<Attachment>(
     {
       priority: 20,
       component: markRaw(VDropdownItem),
+      label: t("core.common.buttons.download"),
+      action: () => {
+        const { permalink } = attachment.value.status || {};
+
+        if (!permalink) {
+          throw new Error("Attachment has no permalink");
+        }
+
+        const a = document.createElement("a");
+        a.href = permalink;
+        a.download = attachment.value.spec.displayName || "unknown";
+        document.body.appendChild(a);
+        a.click();
+        document.body.removeChild(a);
+      },
+    },
+    {
+      priority: 30,
+      component: markRaw(VDropdownDivider),
+    },
+    {
+      priority: 40,
+      component: markRaw(VDropdownItem),
       props: {
         type: "danger",
       },