Revisit argument / input_object validation

[rmosolgo]

Looking through it now, it seems like I could do better on this:

https://github.com/rmosolgo/graphql-ruby/blob/02dd62bcad658a044bb705493cb095778ec89cfc/lib/graphql/static_validation/literal_validator.rb#L71-L76

https://github.com/rmosolgo/graphql-ruby/blob/02dd62bcad658a044bb705493cb095778ec89cfc/lib/graphql/static_validation/rules/required_input_object_attributes_are_present.rb#L37-L44

Could those be DRY'd? Maybe this is part of the larger review of input validation mentioned in #2994, see also https://github.com/rmosolgo/graphql-ruby/issues/3459