Add STB (Belarus standarts) to const-oid

[makavity]

Added OIDS from Republic of Belarus standarts (STB) https://github.com/bcrypto/bake/blob/master/spec/bake-module-v1.asn (for example, one file)

[tarcieri]

Can you leave the pkcs8 changes out for now? It would probably be good to just put those in the bign256 crate.