Validate scenarios against json schema

[kostmo]

Closes #1428

Since the authoritative validation of scenario files is actually performed by virtue of swarm parsing them, this CI job primarily exists to ensure the JSON Schema descriptions are accurate. This is important for two purposes:

• Documentation is generated from the JSON Schema files (Autogenerate parts of scenarios/README.md #1436)
• JSON Schema has integration with VS Code and other IDEs

Testing

Verified that the schema checker action does indeed work by intentionally pushing an invalid scenario file in f789f81.

[xsebek]

It seems I left several things unfinished in #620, thanks for picking this up @kostmo! 👍

Did you manage to integrate the schema to your editor? I use VSCodium YAML extension with this workspace config:

{
    "yaml.schemas": {
        "https://raw.githubusercontent.com/swarm-game/swarm/feature/json-schema-fixes/data/schema/scenario.json": [
            "data/scenarios/**/*.yaml"
        ],
        "https://raw.githubusercontent.com/swarm-game/swarm/feature/json-schema-fixes/data/schema/entities.json": [
            "data/entities.yaml"
        ],
        "https://raw.githubusercontent.com/swarm-game/swarm/feature/json-schema-fixes/data/schema/recipes.json": [
            "data/recipes.yaml"
        ],
    }
}

We should probably note that somewhere (CONTRIBUTING.md or editors?). I am kind of embarrassed that I only wrote that to the previous PR and can't see it in any repo docs. 😅

[byorgey]

Where is all the stuff about subworlds? I don't see that described anywhere in the schemas, but we have testing scenarios which use them.

[byorgey]

I don't understand how this succeeds when the schemas have nothing about subworlds but there are scenarios which make use of subworlds. Do .yaml files still validate when they have extra stuff which is not described in the schema? That would be a problem because that is probably going to be the number one failure mode (someone adds a new feature but forgets to update the schema files).

[kostmo]

Do .yaml files still validate when they have extra stuff which is not described in the schema?

Yes, there are apparently two ways to handle this.

1. Add "additionalProperties": false for every object in the schema. This is what I have done.
2. Use a schema validatation tool that allows specifying this globally. The check-jsonschema tool does not support this. Interestingly, the YAML VS Code extension does have a setting for this: