fix(GraphQL): fix multiple alias in query

[minhaj-shakeel]

Fixes GRAPHQL-806.
Fixes GRAPHQL-793.

This PR extends support for multiple aliases for the same field (except those which are inbuilt) in one query.
For eg:
For the Given Schema:

type Author {
        id: ID!
        posts: [Post!] @hasInverse(field: author)
}

type Post {
        postID: ID!
        title: String! @search(by: [term])
        text: String @search(by: [fulltext])
        isPublished: Boolean @search
        author: Author!
}

The given query:

queryAuthor {
        name
        p1: posts(filter: {isPublished: true}){
          title
          text
        }
        p2: posts(filter: {isPublished: false}){
          title
          text
        }
      }

Earlier the results we picked up only for the first alias for posts i.e p1 and the results into p2 were copied from the p1. This PR fixes that.
Now, p1 should contain all those posts which have isPublished: true and p2 will contain all those posts which have isPublished: false.

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[vmrajas]

Reviewed 5 of 6 files at r1, 1 of 1 files at r2.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @MichaelJCompton and @pawanrawal)