Call on-screen alert using function

[Firjens]

A Lua function to open an alert box on the screen.

• The alert box should enable mouse input.
• The alert box should have an icon
• The alert box should have button(s) which have callback. (No priority)
• The alert box should also have a timer to automatically close.

Implementation idea: Fonction to generate an alert box, which returns an alert UUID (used for tracking stuff like callbacks) and a JSON or something. Code has to send JSON to the webUI which will process it and returns a callback based on the user's input. The callback contains an UUID that the code can use for tracking the callback option.

https://cdn.discordapp.com/attachments/862736696003788831/880052252067393616/unknown.png

[Firjens]

Implemented in branch feature/ui-rework