JellyFileTypeSchema class is delete to maintain compatibility with future IntelliJ versions

[duemir]

It implements extensions that is actually internal. It isn't in 2022.3, but 2024.2 will "fix" it which will make this plugin incompatible.

Testing done

Submitter checklist

• [x] Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• [x] Ensure that the pull request title represents the desired changelog entry
• [x] Please describe what you did
• [x] Link to relevant issues in GitHub or Jira
• [x] Link to relevant pull requests, esp. upstream and downstream changes
• [ ] ~Ensure you have provided tests - that demonstrates feature works or fixes the issue~