Transfer a library to another user or to a department.

• Only the library owner can transfer it.
• To transfer to a department, pass <department_id>@seafile_group as owner; the current user must be admin of that department.
• The new owner's role must allow creating libraries.
• With reshare=true the existing user/group shares are kept and transferred to the new owner; otherwise they are not retained. Share links and upload links are always transferred to the new owner.