portfolio: Fix CryptoID balance issue and assertify tests (#1861)

* portfolio: Fix CryptoID balance issue and assertify tests

* portfolio: Expand context usage, enhance tests and a few other minor improvements

* portfolio: Further improvements and enhance common.IsValidCryptoAddress

* config, portfolio: Use v6.DefaultConfig, switch to context.WithCancel

testdata/configtest.json

@@ -238,6 +238,21 @@
     "ColdStorage": false,
     "SupportedExchanges": ""
    }
+  ],
+  "providers": [
+   {
+    "name": "Ethplorer",
+    "enabled": true
+   },
+   {
+    "name": "XRPScan",
+    "enabled": true
+   },
+   {
+    "name": "CryptoID",
+    "enabled": false,
+    "apiKey": "Key"
+   }
   ]
  },
  "exchanges": [