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

testdata/http_mock/bitstamp/bitstamp.json

@@ -68201,6 +68201,23 @@
     }
    ]
   },
+  "/api/v2/xrp_address/": {
+   "POST": [
+    {
+     "data": {
+      "address": "rDsbeomae4FXwgQTJp9Rs64Qg9vDiTCdBv",
+      "destination_tag": 40687762
+     },
+     "queryString": "",
+     "bodyParams": "key=\u0026nonce=1630130772019126700\u0026signature=4867C3278797DE9AC555D3F3A69076FED19AB28C7CEFBE18A056DAFF2EE7E2EF",
+     "headers": {
+      "Content-Type": [
+       "application/x-www-form-urlencoded"
+      ]
+     }
+    }
+   ]
+  },
   "/api/withdrawal_requests/": {
    "POST": [
     {