Format call chains!

[munificent]

This handles unsplit call chains, fully split ones, as well as block-style calls, like:

target.call(
  argument,
);

This doesn't fully implement the proposal I sketched out because it only allows a single block call. There's a long TODO(tall) comment about whether we want to do that, but I figured it makes sense to do that as a separate iteration since there is so much in here.

But it implements most of it, and I've migrated all of the existing tests over. It ended up being both simpler than the old formatter while also producing better output.

The old formatter has a restriction where the indentation of a piece of code must be fixed regardless of which way it splits. It can't handle:

// Block style, so indent argument +2:
target.property.call(
  argument
);

// Can't do block style, so indent +6:
target
    .slightlyLongerProperty
    .call(
      argument
    );

That leads to it sometimes producing gross output like:

target
    .longProperty
    .anotherLongProperty
    .method(
  wtfIsGoingOnHere,
);

To try to avoid that, it has lots of heuristics during Chunk construction to try to not end up with output like that during line splitting.

The new formatter doesn't need any of those heuristics because it can freely choose indentation during line splitting. 🎉