Add JSON schema validation about jmdict-simplified

[scriptin]

Problems:

• ⚠️ Existing libs for JSON Schema don't work with large files
• everit-org/json-schema provide unhelpful validation messages because no source file location (line number) is given in error messages
• java-json-tools/json-schema-validator don't work with Draft 5+ (do we need that tho?)

[scriptin]

This video https://youtu.be/HHTDCY5uh_M gives a good approach, except that some streaming parser has to be used. Each word can be validated against schema files generated from the type definitions in README. This will both validate the resulting JSON files and type definitions.