add test for numeric separators

Author: erik-krogh

javascript/extractor/tests/es2021/input/numeric.js

@@ -0,0 +1,8 @@
+1_000_000_000           // Ah, so a billion
+101_475_938.38          // And this is hundreds of millions
+
+let fee = 123_00;       // $123 (12300 cents, apparently)
+let fee = 12_300;       // $12,300 (woah, that fee!)
+let amount = 12345_00;  // 12,345 (1234500 cents, apparently)
+let amount = 123_4500;  // 123.45 (4-fixed financial)
+let amount = 1_234_500; // 1,234,500