feat: add uc ctx show command to print the current cluster context (#317)

* feat: add uc ctx show

This only shows the current context and nothing more. On error nothing
is printed (also no error). This is useful to include in your prompt.

See: #314

Signed-off-by: Miek Gieben <miek@miek.nl>

* docs

Signed-off-by: Miek Gieben <miek@miek.nl>

---------

Signed-off-by: Miek Gieben <miek@miek.nl>

cmd/uncloud/context/root.go

@@ -20,6 +20,7 @@ func NewRootCommand() *cobra.Command {
 		NewListCommand(),
 		NewUseCommand(),
 		NewConnectionCommand(),
+		NewShowCommand(),
 	)
 
 	return cmd

cmd/uncloud/context/show.go

@@ -0,0 +1,35 @@
+package context
+
+import (
+	"fmt"
+
+	"github.com/psviderski/uncloud/internal/cli"
+	"github.com/spf13/cobra"
+)
+
+func NewShowCommand() *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "show",
+		Short: "Show current cluster context.",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			uncli := cmd.Context().Value("cli").(*cli.CLI)
+			return show(uncli)
+		},
+	}
+
+	return cmd
+}
+
+func show(uncli *cli.CLI) error {
+	// discard errors, only show the current context, otherwise nothing
+	if uncli.Config == nil {
+		return nil
+	}
+
+	if len(uncli.Config.Contexts) == 0 {
+		return nil
+	}
+	fmt.Println(uncli.Config.CurrentContext)
+
+	return nil
+}