RFC: Allow language Tag support in GraphQL

[amaster507 (Anthony Master)]

@JatinDevDG

@custom : Work normally as with other fields
@hasInverse: Work normally as with other fields
@id : it won’t be applied on such field. @id directive can only be applicable on untagged value i.e. field with @lang directive. *(need discussion)
notNull: field can be made null or not null
@skip: Work normally as with other fields
@include: Work normally as with other fields
@search: Work normally as with other fields
@lambda: Work normally as with other fields
@hasinverse: Work normally as with other fields

This didn’t make sense.

@custom or @lambda combined with @dgraph doesn’t work does it? So combining it with @lang doesn’t make semse.

@hasInverse is for edges not strings so combining it with @lang should throw an error

@search should be limited somehow. What happens when a different index is defined on different language tags.

@skip and @include are query side not schema directives.