support download from sayobot.cn

[undefined-moe]

[CloneWith]

opsu! use classes to define download mirrors. Although configuring search links is a little tricky, you can try to add it yourself if possible:

• Create a new class for Sayobot in downloads/servers
• Import this class in states/DownloadsMenu.java

For reference, I have partially added support for this earlier in my fork. Hope this works!