Added project-based generated files to .gitignore.

[dblock]

Most editors and gradle build generate these files, added them to .gitignore to avoid accidental commits.

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

[nre-ableton]

Thanks!