Move development to mk12/bqn-vscode

[mk12]

Sadly, Raghu Ranganathan (razetime) passed away earlier this year: https://www.arraycast.com/episodes/episode83-jelly.

I would like to maintain the extension. I have contributor permissions on this repo, but not on the extension marketplace, so I have to publish a separate extension with a new name. Here is what I'm doing to package.json:

• publisher: "razetime" → "mk12" so that I can publish
• name: "bqn-language" → "bqn" because it has to be unique
• displayName: "BQN language" → "BQN" because it has to be unique
• description: added (Maintained fork of "BQN language") to the front

I'm also going to continue development in my fork mk12/bqn-vscode so that the GitHub repo matches the publisher, and to ensure I continue to have access to it.