add utils for converting to/from fiat

src/utils/fiatConverter.js

@@ -0,0 +1,18 @@
+const toFiatCurrency = (amount, fiatCurrency, rates) => {
+    // calculate amount in local currency
+    const rate = rates[fiatCurrency];
+
+    let localAmount = parseFloat(amount) * rate;
+    localAmount = Number.isNaN(localAmount) ? '' : localAmount.toFixed(2);
+    return localAmount;
+};
+
+const fromFiatCurrency = (localAmount, fiatCurrency, rates, decimals) => {
+    const rate = rates[fiatCurrency];
+
+    let amount = parseFloat(localAmount) / rate;
+    amount = Number.isNaN(amount) ? '' : amount.toFixed(decimals);
+    return amount;
+};
+
+export { toFiatCurrency, fromFiatCurrency };