Rewrite GraphQLObjectMapper.getInputType to not copy output types.

[bpatters]

There are some limitations in the handling of input types because of the shortcut used in the GraphQLObjectMapper.getInputType copying the existing equivalent outputType. We need this functionality such that getInputType builds it's own full type hierarchy for the type, using caching, instead of trying to copy the outputType.

The primary problem is when the output type equivalent is a TypeReference that hasn't been resolved yet, making the copy fall through and reference the output type. Unfortunately this scenario isn't fixable without doing the above, because the output type hasn't been fully resolved yet and it's structure isn't known.