Minor updates and fixes to the migration script

Why is this change being made?

The migration has recieved a number of updates following other work done on the handbook migration. The most notable fix applies to the redirects. Previously a redirect was setup for almost every page. We now use a regex to setup a single redirect for each migrated section.

The other notable fix was to the report output at the end of the script. Previously the just displayed on the console. This now outputs a markdown document to the desktop of the user running the script as well as outputting it to the console.

Finally the search and replace of the existing handbook content to fix broken links has been updated to roll back links for already migrated content such as values, job-families and teamops.

Author Checklist

• Provided a concise title for this Merge Request (MR)
• Added a description to this MR explaining the reasons for the proposed change, per say why, not just what
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  • If the DRI for the page/s being updated isn’t immediately clear, then assign it to one of the people listed in the Maintained by section on the page being edited
  • If your manager does not have merge rights, please ask someone to merge it AFTER it has been approved by your manager in #mr-buddies
• If the changes affect team members, or warrant an announcement in another way, please post an update in #whats-happening-at-gitlab linking to this MR
  • If this is a change that directly impacts the majority of global team members, it should be a candidate for #company-fyi. Please work with internal communications and check the handbook for examples.

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