enhancement: Add warning if Fade Out event command exists but there is not at least 1 Fade In event command

[lodicolo]

Description

This is not a 1:1 requirement, so you don't need 10 fade ins if you have 10 fade outs (because the fade outs could be inside of conditions, etc).

Intended Use-Case

Warn devs that they are about to make a bone-headed mistake.

Duplicate Check

• This enhancement idea is not a duplicate to the best of my knowledge.

[lodicolo]

This is a follow-up to #2092