Epic: IDE performance configuration experience

[andreafalzetti]

Summary

Improve user experience around configuring Gitpod with a focus on IDE performances

Related issues:

• [jb] add inspections & quickfixes on .gitpod.yml vmoptions config #11089
• [JetBrains] Restart IDE doesn't work #15333
• Detect which plugins are manually installed by not listed in .gitpod.yml #13092

[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.