eslint-plugin-graphql deprecated

[hbruch]

digitransit-ui currently uses eslint-plugin-graphql, which in it's latest version 4.0.0 only supports graphql in the following versions ^0.12.0 || ^0.13.0 || ^14.0.0 || ^15.0.0.

Aseslint-plugin-graphql is deprecated, the project should switch to the recommended graphql-eslint:

[2022-01-25] Note - Upcoming Deprecation Plans: We (Apollo) are working towards fully deprecating this repository. We suggest migrating to the community-supported graphql-eslint. We'll share detailed migration documentation when everything here is ready to be officially deprecated, but just a heads up in case you're planning on adopting anything here for a new project (which you still can of course if this project works for you - support for this project will be minimal however).

[optionsome]

I tried replacing it but couldn't manage to do it quickly while updating relay, and couldn't make sense if the replacement was better or worse but we should indeed update it and get rid of the json format graphql schema file from ui.