CORE-126: Enable scalafmt and format all source code

[davidangb]

This PR has two commits:

1. Enable the scalafmt plugin and define a scalafmt conf; the conf is copied from Rawls https://github.com/broadinstitute/rawls/blob/develop/.scalafmt.conf
2. Run scalafmt on all files. This second commit is large and is machine-generated, no changes by hand. You could choose to not review this commit.

Once this PR is merged, I will follow up with another PR (in draft at #1467) to add enforcement and to ignore the big reformatting in git blame.