feat: match legacy toString output for NumberDecimal type (#17)

Author: tcannon91

snippets/mongocompat/mongotypes.js

@@ -444,6 +444,11 @@ if (typeof NumberDecimal !== 'undefined') {
         NumberDecimal.prototype = {};
     }
 
+    NumberDecimal.prototype.nativeToString = NumberDecimal.prototype.toString
+    NumberDecimal.prototype.toString = function() {
+        return `NumberDecimal("${this.nativeToString()}")`;
+    };
+
     NumberDecimal.prototype.tojson = function() {
         return this.toString();
     };

snippets/mongocompat/test.js

@@ -22,3 +22,6 @@ assert.strictEqual(minLong.bottom, 0);
 assert.strictEqual(minLong.exactValueString, "-9223372036854775808");
 const nl2 = NumberLong("200");
 assert.strictEqual(maxLong.compare(nl2), 1);
+const decimal = NumberDecimal("1.1");
+assert.strictEqual(decimal.toString(), 'NumberDecimal("1.1")');
+assert.strictEqual(decimal.tojson(), 'NumberDecimal("1.1")');