Allow for automatic SSH trust

[rcmurphy]

Is your feature request related to a problem?

Trusting individual workspaces is annoying

Describe the behaviour you'd like

Use an OpenSSH CA to sign all workspace keys, avoiding the need to trust each individual host, and/or set the proper SSHFP DNS records to allow for DNS-based key trust for properly configured clients (probably the more secure of the two options IMO).

[iQQBot]

Unfortunately, SSHFP DNS records-based authentication is not enabled by default for OpenSSH, so this doesn't work well for most users

[loujaybee]

Relates to: #9568

[loujaybee]

Hey @rcmurphy this should now be fixed.

In the new SSH Gateway approaches, you shouldn't get prompted for an SSH fingerprint when opening VS Code Desktop.

https://www.gitpod.io/docs/ides-and-editors/vscode#connecting-to-vs-code-desktop-ssh

This already works for JetBrains. Let me know if this fixes the issue for you, will close the issue 🙏