feat: Add SSH agent forwarding support to coder agent (#1548)

* feat: Add SSH agent forwarding support to coder agent

* feat: Add forward agent flag to `coder ssh`

* refactor: Share setup between SSH tests, sync goroutines

* feat: Add test for `coder ssh --forward-agent`

* fix: Fix test flakes and implement Deans suggestion for helpers

* fix: Add example to config-ssh

* fix: Allow forwarding agent via -A

Co-authored-by: Cian Johnston <cian@coder.com>

cli/configssh.go

@@ -38,6 +38,11 @@ func configSSH() *cobra.Command {
 		Annotations: workspaceCommand,
 		Use:         "config-ssh",
 		Short:       "Populate your SSH config with Host entries for all of your workspaces",
+		Example: `
+  - You can use -o (or --ssh-option) so set SSH options to be used for all your
+    workspaces.
+
+    ` + cliui.Styles.Code.Render("$ coder config-ssh -o ForwardAgent=yes"),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			client, err := createClient(cmd)
 			if err != nil {