[17.0][MIG]cetmix_tower_server: variable widget

[DemchukM]

Summary by CodeRabbit

• New Features

  • Added the "Ace Tower Editor" with context-aware autocompletion for variables and secrets, plus keyboard and typing triggers.

• User Interface

  • Replaced many code/path fields with the new editor for a smoother editing experience.
  • Added an accessible autocomplete popup with search, keyboard navigation, and improved styling/responsiveness.

• Documentation

  • Added a release note describing secret selection from a dropdown in code fields.

• Chores

  • Registered new frontend assets for the editor components.