refactor: unclutter epi_archive print method

[dshemetov]

Checklist

Please:

• Make sure this PR is against "dev", not "main".
• Request a review from one of the current epiprocess main reviewers:
  brookslogan, nmdefries.
• Makes sure to bump the version number in DESCRIPTION and NEWS.md.
  Always increment the patch version number (the third number), unless you are
  making a release PR from dev to main, in which case increment the minor
  version number (the second number).
• Describe changes made in NEWS.md, making sure breaking changes
  (backwards-incompatible changes to the documented interface) are noted.
  Collect the changes under the next release number (e.g. if you are on
  0.7.2, then write your changes under the 0.8 heading).

Change explanations for reviewer

• Removed some metadata prints and combined a few others into a single line
• Added a line that prints key(DT) - c("geo_value", "time_value", "version")
• Added a x$DT %>% print at the end

Magic GitHub syntax to mark associated Issue(s) as resolved when this is merged into the default branch

• Resolves Unclutter epi_archive's print method + add preview of DT #341

[brookslogan]

This is what we had in mind for adding the DT snippet, but these remain:

exclude any redundant information

and

move some other information into a summary method

• The first can be resolved pretty easily here (see code convos).
• Second involves more opinions & could be spun off to a separate lower-priority Issue.

[brookslogan]

question: do you know if Warning: <anonymous>: ... may be used in an incorrect context in the checks was pre-existing?