PR Checklist

• Addresses an existing open issue: just convert story to TS and add missing import. This is a first step for [BUG] PageBreak Story: "Print" does not work. #535
• You have discussed this issue with the maintainers of maxGraph, and you are assigned to the issue.
• The scope of the PR is small enough to review in a single session. PR targeting several issues should be split into separate PRs. Don't create large PR like Examples fixed #88.
• I have added tests to prove my fix is effective or my feature works. This can be done in the form of automatic tests in packages/core/_tests_ or a new or altered Storybook story in packages/html/stories (an existing story may also demonstrate the change).
• I have provided screenshot/videos to demonstrate the change. If no releavant, explain why.
• I have added or edited necessary documentation, or no docs changes are needed.
• The PR title follows the "Conventional Commits" guidelines.

Overview

I converted PageBreaks story to ts and add missing imports. Errors and warns caused by converting story to ts are removed.

Notes

Previously the "Print" button didn't work. Currently the button opens a new tab, but it doesn't show the vertices or edges, so it doesn't solve #535.