fix(cli): show error/hide help for unsupported subcommands (#10760) (#12624)

Fixes #10760 

The coder CLI quietly accepts any subcommand arguments and silently swallows them.

Currently:
```sh
❯ coder | head -n5
coder v2.3.3+e491217

USAGE:
  coder [global-flags] <subcommand>
```

```sh
❯ coder idontexist | head -n5
coder v2.3.3+e491217

USAGE:
  coder [global-flags] <subcommand>
```

Now help output will not be show when there is an unknown subcommand error. Instead users will be given the command for the help output.

```sh
❯ coder idontexist
Encountered an error running "coder", see "coder --help" for more information 
error: unrecognized subcommand "idontexist"
```
```sh
❯ coder iexistbut idontexist
Encountered an error running "coder iexistbut", see "coder iexistbut --help" for more information 
error: unrecognized subcommand "idontexist"
```

Also this stuff: `Encountered an error running "coder iexistbut"... ` gets written to `os.Stdout` in `prettyErrorFormatter{w: os.Stderr, verbose: r.verbose}`, not sure how to test that output.

cli/root_test.go

@@ -60,6 +60,49 @@ func TestCommandHelp(t *testing.T) {
 
 func TestRoot(t *testing.T) {
 	t.Parallel()
+	t.Run("MissingRootCommand", func(t *testing.T) {
+		t.Parallel()
+
+		out := new(bytes.Buffer)
+
+		inv, _ := clitest.New(t, "idontexist")
+		inv.Stdout = out
+
+		err := inv.Run()
+		assert.ErrorContains(t, err,
+			`unrecognized subcommand "idontexist"`)
+		require.Empty(t, out.String())
+	})
+
+	t.Run("MissingSubcommand", func(t *testing.T) {
+		t.Parallel()
+
+		out := new(bytes.Buffer)
+
+		inv, _ := clitest.New(t, "server", "idontexist")
+		inv.Stdout = out
+
+		err := inv.Run()
+		// subcommand error only when command has subcommands
+		assert.ErrorContains(t, err,
+			`unrecognized subcommand "idontexist"`)
+		require.Empty(t, out.String())
+	})
+
+	t.Run("BadSubcommandArgs", func(t *testing.T) {
+		t.Parallel()
+
+		out := new(bytes.Buffer)
+
+		inv, _ := clitest.New(t, "list", "idontexist")
+		inv.Stdout = out
+
+		err := inv.Run()
+		assert.ErrorContains(t, err,
+			`wanted no args but got 1 [idontexist]`)
+		require.Empty(t, out.String())
+	})
+
 	t.Run("Version", func(t *testing.T) {
 		t.Parallel()