Add completion for structure and array variables

[4ian]

• Also update to Jest 29 for GDevelop.js (to allow --watch to works on macOS). Had to update a few things.
• Test if this works for groups.
  • Test what's the impact on group refactoring (add tests for WholeProjectRefactorer::ApplyRefactoringForVariablesContainer)
  • Update group interface to tell that the first object is the one used for completion (or renaming). Also update the wiki.
• Tests for MyVariable[...].Child for arrays and structures