update ci node to 18 and format all files

[philvarner]

Related Issue(s):

n/a

Proposed Changes:

1. Update CI node to 18
2. Move remark configuration to package.json
3. Format all files in line with remark-gfm formatting

PR Checklist:

• This PR is made against the dev branch (all proposed changes except releases should be against dev, not master).
• This PR has no breaking changes.
• I have added my changes to the CHANGELOG
  or a CHANGELOG entry is not required.
• This PR affects the STAC API spec,
  and I have opened issue/PR #XXX to track the change.

[m-mohr]

+1 on the Node updates (maybe better as a separate PR?)

Not so sure whether we want all the noise of the formatting changes in the diff?

[philvarner]

+1 on the Node updates (maybe better as a separate PR?)

Not so sure whether we want all the noise of the formatting changes in the diff?

I put these two "housekeeping" tasks together in the same PR because it was easier. I'd think differently if they were actual changes.