feat: support hetzner cloud server removal

Part of coop-cloud/organising#212.

cli/internal/validate.go

@@ -126,3 +126,31 @@ func ValidateSubCmdFlags(c *cli.Context) bool {
 	}
 	return true
 }
+
+// ValidateServer ensures the server name arg is valid.
+func ValidateServer(c *cli.Context) (string, error) {
+	serverName := c.Args().First()
+
+	serverNames, err := config.ReadServerNames()
+	if err != nil {
+		return serverName, err
+	}
+
+	if serverName == "" && !NoInput {
+		prompt := &survey.Select{
+			Message: "Specify a server name",
+			Options: serverNames,
+		}
+		if err := survey.AskOne(prompt, &serverName); err != nil {
+			return serverName, err
+		}
+	}
+
+	if serverName == "" {
+		ShowSubcommandHelpAndError(c, errors.New("no server provided"))
+	}
+
+	logrus.Debugf("validated '%s' as server argument", serverName)
+
+	return serverName, nil
+}