add way to encode and display per-kernel advice/warnings

[roycewilliams]

The concept of length trade-offs in optimized vs pure kernels is relatively well-revealed in the hashcat interface.

But some kernels have other trade-offs that are implemented for speed. For example, some byte encoding is simplified in the optimized kernel for NTLM that would make some non-ASCII passwords never be cracked, even if they are under the optimized byte limit.

Kernel developers should have a way to specify a note/warning field for their module, that will be displayed to the user, perhaps near where the min/max supported password length is shown at startup.

Any existing trade-offs could then be retroactively documented and communicated to users.