exchanges/engine: Add multichain deposit/withdrawal support (#794)

* Add exchange multichain support

* Start tidying up

* Add multichain transfer support for Bitfinex and fix poloniex bug

* Add Coinbene multichain support

* Start adjusting the deposit address manager

* Fix deposit tests and further enhancements

* Cleanup

* Add bypass flag, expand tests plus error coverage for Huobi

Adjust helpers

* Address nitterinos

* BFX wd changes

* Address nitterinos

* Minor fixes rebasing on master

* Fix BFX acceptableMethods test

* Add some TO-DOs for 2 tests WRT races

* Fix acceptableMethods test round 2

* Address nitterinos

exchanges/exchange_test.go

@@ -2444,3 +2444,11 @@ func TestGetGetURLTypeFromString(t *testing.T) {
 		})
 	}
 }
+
+func TestGetAvailableTransferChains(t *testing.T) {
+	t.Parallel()
+	var b Base
+	if _, err := b.GetAvailableTransferChains(context.Background(), currency.BTC); !errors.Is(err, common.ErrFunctionNotSupported) {
+		t.Errorf("received: %v, expected: %v", err, common.ErrFunctionNotSupported)
+	}
+}