Provide JSON Schema for Drupal yaml files

I think it was a mistake to add JSON schemas to schemastore this way. It's hard to maintain the schemas if you don't have access to them. We should have added just references to the repository with the schemas. Preferably, it should be Drupal core repository.

I propose the following changes.

1. Copy JSON schemas from https://github.com/5n00p4eg/Drupal-json-schemas to Drupal core.
2. Create a pull request for schemastore to replace the schemas.

Since next PhpStorm release it should be possible to reference schemas in the Yaml files.
https://youtrack.jetbrains.com/issue/IDEA-271611

Re #14
Since Drupal added support for service aliases the current JSON schema is no longer valid. Someone has to fix it and make a PR to schema store.