This PR resolves the following broken links:

The first is in the EN lesson finding-places-world-historical-gazetteer

• The problem link is:
  • https://whgazetteer.org/accounts/register/
• Replaced with:
  • https://whgazetteer.org/accounts/login/

--

The second and third are both found across our research pages (en/research, es/investigacion, fr/recherche and pt/pesquisa)

• The second problem link is:
  • https://ach.org/blog/2021/09/fall-2021-programming-historian-book-club
• Replaced with:
  • https://ach.org/news/2021/09/fall-2021-programming-historian-book-club/

--

• The third problem link is
  • https://ach.org/blog/2022/02/ach-programming-historian-workshop-on-twine-in-the-classroom/
• Replaced with:
  • https://ach.org/news/2022/02/ach-programming-historian-workshop-on-twine-in-the-classroom/

Closes#3668

Checklist

• Assign yourself in the "Assignees" menu
• Add the appropriate "Label"
• If this PR closes an Issue, add the phraseCloses #ISSUENUMBER to your summary above
• Ensure the status checks pass: if you have difficulty fixing build errors, please contact our Publishing Manager@anisa-hawes
• Check the Netlify Preview: navigate to netlify/ph-preview/deploy-preview and click 'details' (at right)
• Assign at least one individual or team to "Reviewers"
  • [ ] if the text needs to be translated, please follow thetranslation request guidelines, then assign the relevant language team(s) as "Reviewers" and tag both the team as well as the managing editor in your PR.