v1.23.0

🎉 Features

• Add support for Vega mime type #939, #560
  
• Add margins between items in output area #997, #993
• Add run cell commands to menu #1005

🐛 Bugs

• Don't set default Inspector font size to 0px #991, #996, #1004
• Use px units for inline container styling #1003, #999

👷 Internal Improvements

• Update prettier to the latest version #992
• Update flow-bin to the latest version #1002