Make some validator / viewer online service

[Ostrzyciel]

It would be useful if we could have a web tool that would accept a Jelly file and:

• validate it
• show it in the Protobuf Text Format
• translate it to N-Triples/N-Quads
• show the used options (from the header)
• show whether it's delimited or not

It would be a really nice tool for devs. Probably easier to use for many people than using Jena RIOT from the command line.

Currently we can really only do this as a backend-frontend application, because the Jelly-JVM doesn't really work with browsers. I guess you could try making it work with some JVM-to-Wasm magic, but that may or may not work.

Maybe wait with this until we have a Python or Rust implementation?

[Ostrzyciel]

Related to #27.