Implement warning message when opening .pdex or .pdez files

Created by: SableRaf

Currently, it is possible to open and run a .pdez or .pdex file downloaded from the web without any extra steps. It could be wise to add a warning when opening a bundled sketch/mode/tool/library to tell a user to only run third-party code if they trust the author (similar to VSCode's restricted mode).

Note: Unlike VSCode and its extensions, the PDE won't run arbitrary code just when you open a sketch so this is is not an apples to apples comparison, but since we made it easier to execute arbitrary code on a machine running the PDE, it might still be a good idea to add that extra layer of security.

Edit: this was initially mentioned here https://github.com/processing/processing4/issues/559

Comienza trazando el flujo de apertura y ejecución de archivos .pdex y .pdez incluidos, incluidos sketches, modos, herramientas y bibliotecas. Se considera terminado cuando los usuarios ven una advertencia de confianza antes de ejecutar código de terceros descargado, con un comportamiento alineado con el alcance de seguridad previsto.