Add -Post events firing after operational plot events

[PierreSchwang]

Overview

Closes #3333

Description

Add several events for listening to completed actions, rather than cancelling actions before they happened.

Checklist

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[NotMyFault]

I'm not sure how to feel about the naming conventions yet. One time we have PlayerAutoPlotPostEvent, others use paste tenses, e.g PlotDeletedEvent.
I would suggest to make them consistent using the Post form, e.g. PlayerDeletePostEvent, the former is too similar to a complete different event imo, and the latter propose would also comply with the package the classes are in.

[PierreSchwang]

I'm not sure how to feel about the naming conventions yet. One time we have PlayerAutoPlotPostEvent, others use paste tenses, e.g PlotDeletedEvent. I would suggest to make them consistent using the Post form, e.g. PlayerDeletePostEvent, the former is too similar to a complete different event imo, and the latter propose would also comply with the package the classes are in.

Understandable, yeah. I was not sure about the naming as well, but liked the past tense more, which I can't use in an event after PlayerAutoPlotEvent :/
So I'm gonna migrate all to the "Post" syntax.

[NotMyFault]

Looks good so far, thanks for your contribution.

I have some changes in mind, I'll re-review within the next couple of days.

[NotMyFault]

We may merge it in 24 hours if there is no negative feedback, as per the merge process documentation.