Implement CLI commands

[Isaiah-Turner]

We will need to implement the functionality for the CLI commands. This involves retrieving information from the history archives based on command line arguments, transforming the data that is received using the transform package, and then exporting the data. In addition, all the planned flags should be functional.

• accounts (cmd: implement command for exporting accounts #54)
• ledgers (cmd: implement command for exporting ledgers #55)
• offers (cmd: implement command for exporting offers #56)
• operations (cmd: implement command for exporting operations #57)
• trades ([1](1) cmd: implement command for exporting trades  #58)
• transactions (cmd: implement command for exporting transactions  #59)
• trustlines (cmd: implement command for exporting trustlines  #60)