Hashed strings not 2.0 compliant

[JohnLCaron]

Hashing strings (5.1.4)

"When an input to the function H is a string s, it is encoded as a byte array b(s, len(s)) using UTF-8
encoding. Here, len(s) is the length of the UTF-8 encoding of the string s in bytes."

But we are just using String.encodeToByteArray().

Works as long as we are consistent, but will break vs conformant implementation.

Affects

ContestData.encryptContestData()
KeyCeremonyTrustee.shareEncryption()
AddEncryptedBallot.closeChain()