upgrade Scalafmt (from 1.5.1 to 3.7.4) and reformat sources

[SethTisue]

I spent a certain amount of time tinkering with .scalafmt.conf trying to make the diff smaller

@julienrf do you see any opportunities to minimize the diff further...?

[SethTisue]

I've pushed another commit that switches align.preset from more to none

more does a lot more than it did in Scalafmt 1.x, and it seems overbearing to me and likely to result in ongoing annoying diffs in the future if we keep it on. so while we're reformatting anyway, let's disable it and pay the one-time diffs cost

[SethTisue]

there's a few places where it's inserting an annoying newline after implicit, and I fooled with newlines.implicitParamListModifierXXX and wasn't able to improve it, so I think we can let that go

there were certainly some cases where the alignment was nice-looking, but a lot of others that I found annoying... and most tooling is not likely to preserve the alignment anyway, during development

many of the remaining diffs insert a space to change //foo to // foo, which I can live with

marking as ready for review