Using absolute image paths in Gatsby

This is an answer to the question in this discussion: gatsbyjs/gatsby#31382

"How can I use absolute paths to images in e.g. JSON files and have childImageSharp appear?"

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This solution here is the shortest implementation of https://www.byderek.com/post/a-stackoverflow-question--a-use-case-for-gatsbys-field-extension & their plugin: https://github.com/d4rekanguok/gatsby-schema-field-absolute-path