UI Small Fixes

[bartek-doyensec]

• sometimes none of the Scanner tabs is set to active (i.e. no tabs display the orange border)
• Tab color is slightly different from Burp's other tabs
• When there are no mutations/subscriptions, the empty folder in the results has a "file" icon instead
• Remove 1,2,3 from scanner config page
• Clean up the scanner config page
  • Clean up
  • [ ]Add information about missing URL when using schema file
• Improve editor color scheme in light mode, colors feel a bit too bright