[#7] Add local tool for building database file

Added frostfs-locode-db CLI utility that can generate and view UN/LOCODE
database files. Go package
git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/locode copied to
this repository to eliminate interdependency between frostfs-node and
frostfs-locode-db projects. The process of building database files
reduced to starting make command.

Signed-off-by: George Bartolomey <george@bh4.ru>

main.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+var rootCmd = &cobra.Command{
+	Use:   "frostfs-locode-db",
+	Short: "Command Line Tool to work with FrostFS' UN/LOCODE databases",
+	Long:  "This tool can be used for generating or accessing FrostFS UN/LOCODE databases.",
+}
+
+func ExitOnErr(cmd *cobra.Command, errFmt string, err error) {
+	if err == nil {
+		return
+	}
+
+	if errFmt != "" {
+		err = fmt.Errorf(errFmt, err)
+	}
+
+	const (
+		_ = iota
+		internal
+		aclDenied
+	)
+	cmd.PrintErrln(err)
+	if cmd.PersistentPostRun != nil {
+		cmd.PersistentPostRun(cmd, nil)
+	}
+	os.Exit(internal)
+}
+
+func main() {
+	initUtilLocodeGenerateCmd()
+	initUtilLocodeInfoCmd()
+	rootCmd.AddCommand(locodeGenerateCmd, locodeInfoCmd)
+	err := rootCmd.Execute()
+	if err != nil {
+		ExitOnErr(rootCmd, "", err)
+	}
+}