Use new balance APIs from akkounts

* Use sats integer values instead of floats
* Add lightning Network account balance
* Use icons and titles/descriptions to discern between balance types
* Use more flexible config for balances (to add e.g. RBTC or BTC ecash
  later)

app/helpers/fmt-number.js

@@ -0,0 +1,6 @@
+import { helper } from '@ember/component/helper';
+
+export default helper(function fmtNumber(number) {
+  const lang = navigator.language || navigator.userLanguage;
+  return number.toLocaleString(lang);
+});