make graphql be an external dependency in rollup

[dkent600]

Underscore protocol only allows a single instance of graphql to be present. I believe that simply enforces a restriction of graphql itself. To provide the most options for dApps using multiple packages that each leverage graphql, the client lib can define graphql as an external dependency in the rollup configuration. Then if the dApp chooses to define graphql as a top-level dependency, it may, and as long as it means the client lib's own top-level dependency, the client lib will defer to that. Otherwise, client lib will us the version that it has defined as its own top-level dependency (just as it does now).

Thus I suggest that the client lib define graphql as an external dependency in its rollup configuration.