Updated roadmap and April Release Notes

[amanifarooque]

PR Checklist

• [x] Test Cloud.gov Pages preview for your branch for functionality - make sure all links and buttons work, javascript works as intended, and updates display as expected
  • Release Notes: https://cg-a72b65a7-73f0-4859-a1d7-dc953cf6ade8.sites.pages.cloud.gov/preview/gsa/search-gov-website/fy22q3-roadmap/about/updates/releases/april-2023.html
  • Roadmap: https://cg-a72b65a7-73f0-4859-a1d7-dc953cf6ade8.sites.pages.cloud.gov/preview/gsa/search-gov-website/fy22q3-roadmap/about/updates/roadmap/
• [x] Conduct a HemingwayApp review of the content for plain language. Request plain language review in #helpwanted if needed before merging this PR
• [n/a] Conduct a Lighthouse Audit via Chrome Developer Tools. Identify any issues that must be addressed before merging, and fix
• [x] Ensure no non-public information is published in the commit messages

[amanifarooque]

@dawnpm This PR has both the updated roadmap and the release notes for April. I don't anticipate the release notes changing much after I leave & before the end of the month.