Improved action condition clarity

[Solanya]

When multiple of the same action are defined that could be run at the same time (any two levels in the same campaign that aren't different quest steps of the same quest) and no condition is set on them, we could display a message in the UI, warning of the potential conflict.

The Ctrl-Click to set condition on action/effect could also be replaced by a visible icon somewhere on the line, making it clearer for inexperienced users.