feat: add aria-label attribute for emoji picker button (#113)

为标签按钮添加了aria-label字段，增强无障碍

```release-note
为标签按钮添加了aria-label字段，增强无障碍
```

packages/comment-widget/src/emoji-button.ts

@@ -83,7 +83,7 @@ export class EmojiButton extends LitElement {
  }
 
  override render() {
- return html`<button class="emoji-button" type="button">
+ return html`<button class="emoji-button" type="button" aria-label="选择表情">
  ${this.emojiLoading
  ? html`<icon-loading></icon-loading>`
  : html`<icon-emoji @click=${this.handleOpenEmojiPicker}></icon-emoji>`}