Elaborate Serializing and Deserializing of Data

[andrewpeters9]

There seems to be some inconsistencies with how data is serialized and deserialized in some of the Metamask keyring libraries.

For the Trezor keyring:

• this.paths is included in serialization, but not in deserialization
• this.hdk can/should be serialised and deserialised
  • Only the publicKey and chainCode need to be serialised/deserialised
• this.hdPath can be changed via deserialization without triggering the this.setHdPath method
• Some "resetting" of data can be refactored (i.e., see forgetDevice, setHdPath and the constructor)
• Setting this.hdKey can be refactored via a setHdKey method