feat: deposit

[hhow09]

Feature

• user should be able to deposit money
• add account type external for double entry bookkeeping
• when create bank account, corresponding external account of same currency should be created.
• when deposit
  1. create transfer (from user ext account to user bank account)
  2. user's external account -= amount
  3. user's bank account += amount

TODO

• connect to message queue to receive deposit event.
• when user deposit success, should notify user.