Each "message" requiring a user confirmation has a unique `type`
property. These `type` properties have all been added as enums, and the
enum is now used wherever the literal string was used previously.
Implement `eth_decrypt` and `eth_getEncryptionPublicKey`. This allows decryption backed by the user's private key. The message decryption uses a confirmation flow similar to the messaging signing flow, where the message to be decrypted is also able to be decrypted inline for the user to read directly before confirming.
Erik Marks
Mark Stacey
Konstantin