fix: display the correct response for coder list (#16547)

Closes https://github.com/coder/coder/issues/16312

We intend to modify the behavior of the CLI handler based on the
specified output format. However, the output format is currently only
accessible within the `OutputFormatter` structure. Therefore, I propose
extending `OutputFormatter` by introducing a public `FormatID` method,
which will allow us to retrieve the format identifier and use it to
customize the behavior of the CLI handler accordingly.

cli/list.go

@@ -112,7 +112,7 @@ func (r *RootCmd) list() *serpent.Command {
 				return err
 			}
 
-			if len(res) == 0 {
+			if len(res) == 0 && formatter.FormatID() != cliui.JSONFormat().ID() {
 				pretty.Fprintf(inv.Stderr, cliui.DefaultStyles.Prompt, "No workspaces found! Create one:\n")
 				_, _ = fmt.Fprintln(inv.Stderr)
 				_, _ = fmt.Fprintln(inv.Stderr, "  "+pretty.Sprint(cliui.DefaultStyles.Code, "coder create <name>"))