Fix sum encoding for unary ref alternative
Fix sum encoding for unary ref alternative

In case of unary non-record alternative we retain field's
name in case we need to $ref it when constructing schema for
sum type. Note that this only affects sum types, e.g.

-- some type with named schema to $ref
data A = ...

-- schema for B will reuse schema for A, not $ref to it
data B = B A deriving (Generic, ToSchema)

-- schema for C will $ref A for C1 constructor
data C = C1 A | ... deriving (Generic, ToSchema)

GetShopTV/swagger2