Validate JSON files against schemas in `make test` and CI

[lgarron]

The best tool I'm aware of for this is ajv, which has a CLI:

bun x ajv-cli validate -s "node_modules/cubing/experimental-json-schema/kpuzzle/KPuzzleDefinition.schema.json" -d "samples/json/2x2x2/2x2x2.kpuzzle.json"

We need to determine which files to validate against which schemas, without false negatives. (For example, newly added files should not be skipped just because they e.g. don't have a $schemafield. We should probably require and validate a schema for everyjson` file in in the directories containing definitions and patterns.)