[WIP] Port of additional music moods (#4968)

[Birdulon]

Rework war calculations, add war2, winning, losing music moods related to higher combat levels and large attrition ratios, respectively. Rework dynamic transition logic to accomodate more than just peace<->war.
This is a considerable refactor of my additions of my personal widget linked in #4968, which forked in June 2020. It is nowhere near as used and tested as that, but should be a little bit nicer than it by the end.

[sprunk]

Splitting off as many small standalone changes as possible into commits would be helpful, a monolith is a bit harder to review.

[GoogleFrog]

That might not be necessary. We could just replace one black box with another - that sounds easier. It's relatively safe to do with a widget as I could just run it for a month and see if anything comes up.