feat: TRAC-642 expose v3 runtime (#400)

Author: jairo-bc

index.js

@@ -1,5 +1,6 @@
 'use strict';
 const HandlebarsV3 = require('handlebars');
+const HandlebarsV3Runtime = require('handlebars/runtime.js');
 const HandlebarsV4 = require('@bigcommerce/handlebars-v4');
 const HandlebarsV4Runtime = require('@bigcommerce/handlebars-v4').runtime;
 const helpers = require('./helpers');
@@ -43,6 +44,9 @@ class HandlebarsRenderer {
             case 'v4-runtime':
                 this.handlebars = HandlebarsV4Runtime;
                 break;
+            case 'v3-runtime':
+                this.handlebars = HandlebarsV3Runtime;
+                break;
             case 'v4':
                 this.handlebars = HandlebarsV4.create();
                 break;