Function getUnreadCountByTag

getUnreadCountByTag(
tagId: string,
containMuted: boolean,
): Promise<RCResult<number>>
根据标签获取未读消息数
Parameters
- tagId: string
  标签 id
- containMuted: boolean
  是否包含免打扰
Returns Promise<RCResult<number>>
Example: 根据标签获取未读消息数示例：
```
const tagId = 'tagId';
const containMuted = false;
const res = await RongIMLib.getUnreadCountByTag(tagId, containMuted);
console.log('根据标签获取未读消息数结果：', res);
```