Feature request: Add SM4 encryption

[LeonXu260]

@idrassi There is a recent publication that I've come across that China has publishes its own encryption algorithm named "SM4". Here is an article that talks about SM4 algorithm.

Desired behavior

It is possible to add SM4 as part of the Encryption Algorithm that can be used.

VeraCrypt version: VeraCrypt 1.25.9

Operating system and version: Windows 11 Build 22000.556

System type: 64 bit

[alt3r-3go]

@LeonXu260, what would justify adding that additional algorithm into VC and the respective development/testing time investment? It's IMHO highly unlikely VC is going to be used in China's governmental agencies, or other places where having SM4 would be mandated.