Arby interactive integration

[kilrau]

• [x] arby runs in separate container
• [ ] on first run (create): choose exchange via CLI (1,2,3), last option I don't want to connect to an exchange. If exchange is chosen, setup asks to copy/paste API credentials + checks if they work. Entered values get persisted in .conf as usual:

  [arby]
  enable = 1
  BinanceAPIKey =
  BinanceAPISecret =

• [ ] arby container is brought up only upon [arby] enable = 1 is written to the config. If arby is enabled, but exchange credentials are missing, xud-docker should prompt with above "Enter API Key" prompt.
• [ ] xud-docker checks arby container the same way it checks others when xud-ctl is entered (e.g. if [arby] enable = 1, but there is no arby container -> bring it up)
• [ ] validity of exchange credentials (try actual ccxt connection) is done on every start of xud-docker. Print error if that fails. Might be better for arby to do that natively and throw and xud-docker taking care of printing.

[ghost]

validity of exchange credentials (try actual connection to binance & co) is done on every start of xud-docker. Has to print error if that fails.

This should be handled by arby and printed in the logs.

The config should also include the margin for OpenDEX orders: https://github.com/ExchangeUnion/market-maker-tools/blob/master/.env-example-arby#L7