Feature: Provide data transfer interface

[cipchk]

Checklist

• I've searched for similar issues and couldn't find anything matching
• I've discussed this feature request in the OpenIMSDK Slack and got positive feedback

Is this feature request related to a problem?

None

Problem Description

Solution Description

When a customer service leaves, we hope to transfer the chat data (include:conversation, friends, group etc) to other customer service.

Benefits

This can better solve the problem of resignation.

Potential Drawbacks

No response

Additional Information

No response

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[skiffer-git]

You can handle this using an API, for example, by using http://x.x.x.x:10002/friend/import_friend