Display toasts when using push_error() or push_warning() in a script

[Calinou]

This only applies to scripts running within the editor itself, such as editor plugins and @tool scripts.

Text-based logging will also display those errors as userspace errors, as opposed to internal engine errors.

• This partially addresses Expose `EditorToaster` API for plugins godot-proposals#6452 (there's no way to create "info" toasts until we implement Add INFO_PRINT() and push_info() for important but "expected" messages godot-proposals#1378).

Testing project: test_toast.zip

Preview

[dalexeev]

I think Output Log and Toast Notifications have different purposes. The first is for a potentially large number of messages, which you can then leisurely read for debugging. The second is for a small number of messages that disappear very quickly, mostly to get the user's attention, but without requiring them to take any action.

It seems to me that it is not good to mix these two functions without the ability to control exactly where the message will be shown. Especially if we later expose the EditorToaster singleton.

push_* functions are for the debugger, which is not used when executing code in the editor. In theory, these functions should not be used in plugins/tools at all, but messages are displayed in the Output Log instead. People are used to this and this change can be inconvenient in some cases. Users may not want messages to be duplicated in toast notifications. Also, users may ask why toasts are not used when the code is executed in the game.

[KoBeWi]

Editor toaster has been exposed in #98680. I think it's better to give users more control on how the messages appear and this PR ties editor log with the toaster. It's usually not desired.

[Calinou]

Closing per @KoBeWi's comment.