Revisit use of GitHub Marketplace and GitHub Student Developer Pack

[jldec]

https://github.com/marketplace/gitpod-io
https://education.github.com/pack/

• Correct copy for Personal plan (remove references to private repos)
• Correct copy and icon for Student pack
• [payment-endpoint] Revise handling of GitHub plans #5702
• [payment-endpoint] GitHub integration: reconcilePlan is broken #6531
• Handle paid plans through Gitpod dashboard

screenshots Nov 11, 2021

[stale]

This issue has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs. Thank you for your contributions.

[jldec]

Closing in favor of #14025