Feature Request: Replace /server command to allow filter servers by permissions

When you do `/server`, it shows the server you are currently in and all thee available servers along with the number of connected players when you hover.

I think on that list it should hide the servers for which you don't have permission

Look at the command handling for `/server` in the plugin code, likely in a class like ServerCommand. The list of servers is fetched from the Velocity API. Filter this list by checking the player's permissions, probably using a permission node pattern like 'serverpermissions.server.'. Test by joining a server without permission and verifying it's hidden from the list.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.