$stageVariables are not supported in tempaltes

[matthias-pichler]

It would be great if one could pass stageVariables into the mapping function when calling.

var mappingTemplate = require('api-gateway-mapping-template')
 
var vtl = '$input.json(\'$.data\')';
var payload = '{"data": {"url": "https://github.com/ToQoz/api-gateway-mapping-template"}}';
 
var result = mappingTemplate({template: vtl, payload: payload, stageVariables: { foo: "bar" }})