GHSA-mcqq-fqgf-rxwm: Coder vulnerable to SSH config injection via unsanitized server-supplied values in `coder config-ssh`

Coder's `coder config-ssh` command didn't properly check server-supplied SSH settings (HostnameSuffix, SSHConfigOptions) before writing them to the user's SSH configuration file, allowing a malicious or compromised server to inject arbitrary SSH configuration directives. An attacker controlling the server could inject commands like ProxyCommand to execute arbitrary code on a developer's workstation with that user's privileges.