Unify all code for name bans in new class `CNameBans` in the existing `name_ban.cpp/h` files. The previously global function `IsNameBanned` is now the member function `CNameBans::IsBanned`. The existing name ban tests are extended for the `CNameBans` class.
Move `CNameBan` constructor definition to source file to avoid including `system.h` in the header file. Use `bool` instead of `int` for `m_IsSubstring`. Reorder `CNameBan` constructor arguments and remove unnecessary default value.