[Feature Request] Add propagateElements method and events in 3.2

[putyourlightson]

Feature request to add a propagateElements method and events to the Elements service in Craft 3.2.

Something similar was done with resaveElements in 5b0cd57 and the same logic could hopefully be applied to propagating elements. I'd be happy to submit a PR but I assume you probably want to follow your own pattern in the implementation of this.

[putyourlightson]

FYI since 3.2.0-alpha.4 changed the behaviour back to propagating elements immediately on save, this is less of a priority than previously, and possible not even necessary.

craft\services\Elements::saveElement() now immediately propagates elements if $propagate is true, as it used to.

[brandonkelly]

I’ll probably land somewhere in between, where most of the time we propagate over a background task. But there were cases where the blanket approach was an issue.

[putyourlightson]

Ok, I'll wait and see where this ends up, thanks!

[brandonkelly]

Added propagateElements() for the next 3.2 Alpha release.

[putyourlightson]

Thanks Brandon!