Redesign HWKeyCrypter

[oliveraemmer]

• [x] Implement in bitcoin-wallet or bitcoinJ? -> bitcoin-wallet

Implement and redesign current HWKeyCrypter

• [x] Copy HWKeyCrypter from Project 2
• [x] Add biometric authentication when creating the KeyStore instance
• [x] Error handling if the phone does not support biometric auth
• [x] Handle unused password in deriveKey() method (add clear information in the comments that the password is unused)
• [x] Handle KeyStore key reference (Store key reference as class field and return it as AesKey in deriveKey())
• [x] Access KeyStore based on provided AesKey key reference in decrypt() and encrypt()

[oliveraemmer]

Handle KeyStore key reference (Store key reference as class field and return it as AesKey in deriveKey()) -> Reference is implemented as application constant