Epic: Deprecate projects under personal accounts

[jldec]

This simplifies the model, so that new projects live only under a team, and not under a personal account

Benefits

1. A project under a user account cannot not be shared, and its URL only works for that user
2. Teams are a more flexible container e.g. to manage ownership and billing for projects
3. The UI for the personal account context becomes unnessary, and can be replaced by a "New Team" button for users who do not have a teams.

Users with existing personal projects

This epic does not move existing personal projects under a team. Users with existing personal projects will continue to have access to those as before.

• Remove the ability to create new personal projects through the dashboard #14036
• https://github.com/gitpod-io/website/issues/2934
• Clarify notification to "remove projects under personal accounts in Q1'2023." #13892
• Change new project flow to remove the personal account option #14037