GraphQL Support
**Which version of the plugin are you using?**
[ ] Data Populator for Sketch
[X] Data Populator for Adobe XD

**Is your feature request related to a problem? Please describe.**
Awesome plugin, and hoping you'd consider the ability to consume GraphQL APIs so you can have granular support of the elements returned. GraphQL definition here: https://graphql.org/

**Describe the solution you'd like**
the ability to add a body with the graphql query to the Data Source panel, and submit as a POST command. 

**Describe alternatives you've considered**
Alternative is to run the query elsewhere and link to the results as static json

**Additional context**
GraphQL definition here: https://graphql.org/
Queries look like this;
{
  hero {
    name
    height
  }
}
