TEC-5058 Add ESM upsell

[pattihis]

🎫 Ticket

TEC-5058

🗒️ Description

Added the Events Schedule Manager into the the list of our plugins that are shown in the Help and in the App Shop admin pages.

✔️ Checklist

• [x] Changelog entry in the readme.txt file.
• [ ] Code is covered by NEW wpunit or integration tests.
• [ ] Code is covered by EXISTING wpunit or integration tests.
• [ ] Are all the required tests passing?
• [x] Automated code review comments are addressed.
• [ ] Have you added Artifacts?
• [ ] Check the base branch for your PR.
• [ ] Add your PR to the project board for the release.