[#1906] Fix duplicate form definitions after importing a form

[vaszig]

Closes #1906

Changes

• Added regression tests for import and export with a file component as an input
• Removed the dynamic rewrite_formio_components from the export flow as we don't care about the request at this point

Checklist

Check off the items that are completed or not relevant.

• Impact on features

  • [x] Checked copying a form
  • [x] Checked import/export of a form
  • [x] Config checks in the configuration overview admin page
  • [x] Problem detection in the admin email digest is handled

• Release management

  • [x] I have labelled the PR as "needs-backport" accordingly

• I have updated the translations assets (you do NOT need to provide translations)

  • [x] Ran ./bin/makemessages.sh
  • [x] Ran ./bin/compilemessages_js.sh

• Commit hygiene

  • [x] Commit messages refer to the relevant Github issue
  • [x] Commit messages explain the "why" of change, not the how