Create Coinbase Advanced Trade Exchange Adapter

[gazbert]

Coinbase Pro is dead:
https://www.coinbase.com/en-gb/blog/hello-advanced-trade-goodbye-coinbase-pro

Coinbase Advanced Trade replaces it:
https://help.coinbase.com/en/coinbase/trading-and-funding/advanced-trade/what-is-advanced-trade

New Advanced Trade API docs:
https://docs.cdp.coinbase.com/advanced-trade/docs/welcome

New Advanced REST API:
https://docs.cdp.coinbase.com/advanced-trade/docs/api-overview

Auth procedure:
https://docs.cdp.coinbase.com/advanced-trade/docs/rest-api-auth