fix: Use field name in json type schema if json tag is missing

[erezrokah]

Summary

I'm working on validating some data (internal issue https://github.com/cloudquery/cloudquery-issues/issues/2971) using the json type schema and noticed a bug (noticeable on AWS where structs don't have json tags).
We should not use the name transformer to get the name as it defaults to ToSnake when a json tag is missing.
Instead we should mimic the JSON marshaling default behavior to use the field name as is.

A better approach can be to create an instance of the type, marshal it to JSON, then use that for the names. Open to ideas how to do that using reflection, we a caveat that we might need to initialize it using non zero values that can be omitted

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