fix(formatNumber): custom format with ? as literal

Author: danielkaradachki

src/numbers/custom-number-format.js

@@ -4,7 +4,7 @@ import round from '../common/round';
 
 const CURRENCY_SYMBOL = "$";
 const PERCENT_SYMBOL = "%";
-const PLACEHOLDER = "??";
+const PLACEHOLDER = "__??__";
 const CURRENCY = "currency";
 const PERCENT = "percent";
 const POINT = ".";

test/numbers.js

@@ -435,6 +435,11 @@ describe('custom formatting', () => {
         expect(formatNumber(10, "# \\%")).toEqual("10 %");
     });
 
+    it("formats with question mark as literal", () => {
+        expect(formatNumber(10, "?\\$#")).toEqual("?$10");
+        expect(formatNumber(10, "\\?\\$#")).toEqual("?$10");
+    });
+
     it("formats with quote as literal", () => {
         expect(formatNumber(10, "# \"%\"")).toEqual("10 %");
     });