About GraphQL body support

[jukbot]

I've the issue when using this tool to parse my postman collection with graphql body included. The output document show an empty request body. This tool is great and work very well. It's good to include body tabs in doc.

[omarlopesino]

This would be nice to have. I work in a graphql project and this feature helps to show graphql requests. This MR does the work: #78 It is ready to review, any help is appreciated. Thanks!