fix #2465 remote model with omitempty

[mstephano]

Fixes #2465

Running go generate creates unnecessary resolvers when:

1. using a remote model that has a json tag with omitempty, and the value of json is different than the attribute name
2. the remote package is in autobind in gqlgen.yml file, and also struct_tag: json is used
3. these new resolvers need to be implemented but my expected result is to be able to use my model right away

The reason I am having this error is because I am adding gqlgen to an existing repo with many models. I want these models to stay in the files they are right now, not having them "duplicated" under /graph/model.

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

Here is a video demonstrating my integration test:

Screen.Recording.2022-12-13.at.11.53.37.PM.mov

[coveralls]

Coverage increased (+0.003%) to 75.672% when pulling c57921a on mstephano:master into da43147 on 99designs:master.