lint: copy .lintr from epidatr

[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

• Mostly line length 120, cyclocomp off
• Repo changes, no need for changelog/version

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

[nmdefries]

Looks good. How does this get run?

[dshemetov]

If you have an IDE linter or if you do lintr::lint_package() it should automatically get read. Nothing automated or in CI at this point.