Homogenize various type class names

[teh]

From discussion in #92 (comment)

we don't have super consistent naming so we could do better:

$ gg -h "^class " | sort | uniq
class BuildFieldResolver m fieldResolverType where
class Defaultable a where
class FromValue a where
class GenericAnnotatedInputType (f :: Type -> Type) where
class GenericEnumValues (f :: Type -> Type) where
class GenericFromValue (f :: Type -> Type) where
class GenericInputObjectFieldDefinitions (f :: Type -> Type) where
class GraphQLEnum a where
class GraphQLError e where
class HasAnnotatedInputType a where
class HasAnnotatedType a where
class HasArgumentDefinition a where
class HasFieldDefinition a where
class HasFieldDefinitions a where
class HasInterfaceDefinition a where
class HasInterfaceDefinitions a where
class HasName a where
class HasObjectDefinition a where
class HasResolver m a where
class RunFields m a where
class RunUnion m union objects where
class ToValue a where
class UnionTypeObjectTypeDefinitionList a where

[jml]

I think it's OK for ToValue and FromValue to be different.

Likewise, I think the Generic ones are implementation details and don't need to be exposed.

I don't think there'll ever be more than one human being who knows what BuildFieldResolver does / is for, but I'm happy to be surprised there.

IIUC, RunFields and RunUnion are also implementation details.