update eslint's comma-dangle rule to always-multiline.

[lieut-data]

Summary

update eslint's comma-dangle rule to always-multiline.

This includes the output of invoking yarn fix to fix everything. No
other changes are included.

Checklist

• Ran make check-style to check for style errors (required for all pull requests)
• Ran make test to ensure unit and component tests passed

[lieut-data]

This is the only change of significance.

[lieut-data]

As part of this, I'm investigating the best way to streamline rebases for feature branches. Once I have a plan for that, I'll post here and unblock the review/merge.

[lieut-data]

To avoid merge conflicts, and assuming this commit goes in as COMMIT it should suffice to:

# Rebase as normal from the commit prior, resolving any necessary merge conflicts
git rebase COMMIT^
# Now rebase against the eslint changes, using a strategy that ignores 
# upstream changes when merge conflicts occur. Given the previous, 
# successful rebase, this should only be the newly added trailing commas.
git rebase --strategy-option=theirs COMMIT
# If any files were deleted in the local branch, the rebase may be interrupted
# and the files will need to be marked for deletion again.
git status --porcelain | awk '{if ($1=="UD") print $2}' | xargs git rm
git rebase --continue
# Once the rebase has finished, run another linting pass and commit
yarn fix
git add --all
git commit -m 'adopt updated eslint changes'
# The `master` branch will have moved on as well, so another normal 
# rebase against `master` is in order.
git rebase master