Support ndc-spec 0.1.6 (#137)

[hgiasac]

Cherry-pick #137

[github-actions]

Package	Line Rate	Health
github.com/hasura/ndc-sdk-go/cmd/hasura-ndc-go/command/internal	54%	➖
github.com/hasura/ndc-sdk-go/cmd/hasura-ndc-go/command	58%	➖
github.com/hasura/ndc-sdk-go/cmd/hasura-ndc-go	79%	✔
github.com/hasura/ndc-sdk-go/cmd/hasura-ndc-go/version	62%	➖
github.com/hasura/ndc-sdk-go/connector	52%	➖
github.com/hasura/ndc-sdk-go/example/reference	65%	➖
github.com/hasura/ndc-sdk-go/internal	53%	➖
github.com/hasura/ndc-sdk-go/scalar	98%	✔
github.com/hasura/ndc-sdk-go/schema	49%	➖
github.com/hasura/ndc-sdk-go/utils	27%	❌
Summary	52% (5441 / 10432)	➖

Minimum allowed line rate is 40%