Add JSON schema for AGLint config files

[scripthunter7]

AGLint config files can be validated in the VSCode editor if the following field is filled in the package.json file of the extension:

https://code.visualstudio.com/api/references/contribution-points#contributes.jsonValidation

If we switch to zod, we can export zod schema easily during AGLint build via https://www.npmjs.com/package/zod-to-json-schema (so ​​no need to maintain a redundant JSON file)

Idea from: AdguardTeam/AGLint#210