Login Module - Graphql

[Arjun-sna]

Add graphql equivalent of login REST api #38 . Send appropriate error and success data.

[prasanna1211]

@Arjun-sna Just to add to this to make it clear for all, Both the versions of API will be available but GraphQL won't use REST directly. Instead it will interact db on own.

[Arjun-sna]

We have planned to have both the graphQL and REST versions of the API since having only graphQL is way easier than the traditional REST approach. For learning purpose, we can build the REST based versions too.

So keep both apis(graphQl and REST) independent so that clients are free to use any one or both interchangeably of their choice based on their requirement.