feat(cli): add --client flag to kargo version

This adds support for supplying a `--client` flag to `kargo version`,
which avoids the command from attempting to collect version information
from the API server.

```console
$ kargo version --client
Client Version: devel+unknown.dirty
```

In addition, the order of collecting information has been adjusted to
allow partial information to be printed when the API server can not
be reached before returning an error.

```console
$ kargo version
Client Version: devel+unknown.dirty
Error: get version info from server: unavailable: dial tcp [::1]:30081: connect: connection refused

$ kargo version --output yaml
apiVersion: kargo.akuity.io/v1alpha1
cli:
  buildTime: "2024-02-22T11:18:51Z"
  compiler: gc
  gitTreeDirty: true
  goVersion: go1.21.3
  platform: linux/amd64
  version: devel+unknown.dirty
kind: ComponentVersions
Error: get version info from server: unavailable: dial tcp [::1]:30081: connect: connection refused
```

However, in case `--output` is provided and the printer itself runs
into an issue, this error takes precedence.

```console
$ kargo version --output go-template --template '{{ .cli.version }'
Error: new printer: error parsing template {{ .cli.version }, template: output:1: unexpected "}" in operand
```

Signed-off-by: Hidde Beydals <hidde@hhh.computer>

cmd/cli/version.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"encoding/json"
 	"fmt"
 
@@ -29,32 +30,24 @@ func newVersionCommand(
 		Use: "version",
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ctx := cmd.Context()
+			printToStdout := ptr.Deref(opt.PrintFlags.OutputFormat, "") == ""
+
+			cliVersion := typesv1alpha1.ToVersionProto(versionpkg.GetVersion())
+			if printToStdout {
+				fmt.Println("Client Version:", cliVersion.GetVersion())
+			}
 
 			var serverVersion *svcv1alpha1.VersionInfo
-			if !opt.UseLocalServer {
-				if cfg.APIAddress != "" && cfg.BearerToken != "" {
-					kargoSvcCli, err := client.GetClientFromConfig(ctx, cfg, opt)
-					if err != nil {
-						return errors.Wrap(err, "get client from config")
-					}
-					resp, err := kargoSvcCli.GetVersionInfo(
-						ctx,
-						connect.NewRequest(&svcv1alpha1.GetVersionInfoRequest{}),
-					)
-					if err != nil {
-						return errors.Wrap(err, "get version info from server")
-					}
-					serverVersion = resp.Msg.GetVersionInfo()
-				}
+			var serverErr error
+			if !opt.UseLocalServer && !opt.ClientVersionOnly {
+				serverVersion, serverErr = getServerVersion(ctx, cfg, opt)
 			}
-			cliVersion := typesv1alpha1.ToVersionProto(versionpkg.GetVersion())
 
-			if ptr.Deref(opt.PrintFlags.OutputFormat, "") == "" {
-				fmt.Println("Client Version:", cliVersion.GetVersion())
+			if printToStdout {
 				if serverVersion != nil {
 					fmt.Println("Server Version:", serverVersion.GetVersion())
 				}
-				return nil
+				return serverErr
 			}
 
 			printer, err := opt.PrintFlags.ToPrinter()
@@ -68,14 +61,40 @@ func newVersionCommand(
 			if err != nil {
 				return errors.Wrap(err, "map component versions to runtime object")
 			}
-			return printer.PrintObj(obj, opt.IOStreams.Out)
+
+			if err := printer.PrintObj(obj, opt.IOStreams.Out); err != nil {
+				return errors.Wrap(err, "printing object")
+			}
+			return serverErr
 		},
 	}
+
 	opt.PrintFlags.AddFlags(cmd)
 	option.InsecureTLS(cmd.PersistentFlags(), opt)
+	option.ClientVersion(cmd.PersistentFlags(), opt)
 	return cmd
 }
 
+func getServerVersion(ctx context.Context, cfg config.CLIConfig, opt *option.Option) (*svcv1alpha1.VersionInfo, error) {
+	if cfg.APIAddress == "" || cfg.BearerToken == "" {
+		return nil, nil
+	}
+
+	kargoSvcCli, err := client.GetClientFromConfig(ctx, cfg, opt)
+	if err != nil {
+		return nil, errors.Wrap(err, "get client from config")
+	}
+	resp, err := kargoSvcCli.GetVersionInfo(
+		ctx,
+		connect.NewRequest(&svcv1alpha1.GetVersionInfoRequest{}),
+	)
+	if err != nil {
+		return nil, errors.Wrap(err, "get version info from server")
+	}
+
+	return resp.Msg.GetVersionInfo(), nil
+}
+
 func componentVersionsToRuntimeObject(v *svcv1alpha1.ComponentVersions) (runtime.Object, error) {
 	data, err := protojson.Marshal(v)
 	if err != nil {

internal/cli/option/flag.go

@@ -19,6 +19,10 @@ func LocalServer(fs *pflag.FlagSet, opt *Option) {
 	fs.BoolVar(&opt.UseLocalServer, "local-server", false, "Use local server")
 }
 
+func ClientVersion(fs *pflag.FlagSet, opt *Option) {
+	fs.BoolVar(&opt.ClientVersionOnly, "client", false, "If true, shows client version only (no server required)")
+}
+
 func Project(fs *pflag.FlagSet, opt *Option, defaultProject string) {
 	fs.StringVarP(&opt.Project, "project", "p", defaultProject, "Project")
 }

internal/cli/option/option.go

@@ -18,6 +18,8 @@ type Option struct {
 	LocalServerAddress string
 	UseLocalServer     bool
 
+	ClientVersionOnly bool
+
 	Project string
 
 	IOStreams  *genericclioptions.IOStreams