[#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>

pkg/locode/db/point.go

@@ -0,0 +1,93 @@
+package locodedb
+
+import (
+	"fmt"
+	"strconv"
+
+	locodecolumn "git.frostfs.info/TrueCloudLab/frostfs-locode-db/pkg/locode/column"
+)
+
+// Point represents a 2D geographic point.
+type Point struct {
+	lat, lng float64
+}
+
+// NewPoint creates, initializes and returns a new Point.
+func NewPoint(lat, lng float64) *Point {
+	return &Point{
+		lat: lat,
+		lng: lng,
+	}
+}
+
+// Latitude returns the Point's latitude.
+func (p Point) Latitude() float64 {
+	return p.lat
+}
+
+// Longitude returns the Point's longitude.
+func (p Point) Longitude() float64 {
+	return p.lng
+}
+
+// PointFromCoordinates converts a UN/LOCODE coordinates to a Point.
+func PointFromCoordinates(crd *locodecolumn.Coordinates) (*Point, error) {
+	if crd == nil {
+		return nil, nil
+	}
+
+	cLat := crd.Latitude()
+	cLatDeg := cLat.Degrees()
+	cLatMnt := cLat.Minutes()
+
+	lat, err := toDecimal(cLatDeg[:], cLatMnt[:])
+	if err != nil {
+		return nil, fmt.Errorf("could not parse latitude: %w", err)
+	}
+
+	if !cLat.Hemisphere().North() {
+		lat = -lat
+	}
+
+	cLng := crd.Longitude()
+	cLngDeg := cLng.Degrees()
+	cLngMnt := cLng.Minutes()
+
+	lng, err := toDecimal(cLngDeg[:], cLngMnt[:])
+	if err != nil {
+		return nil, fmt.Errorf("could not parse longitude: %w", err)
+	}
+
+	if !cLng.Hemisphere().East() {
+		lng = -lng
+	}
+
+	return &Point{
+		lat: lat,
+		lng: lng,
+	}, nil
+}
+
+func toDecimal(intRaw, minutesRaw []byte) (float64, error) {
+	integer, err := strconv.ParseFloat(string(intRaw), 64)
+	if err != nil {
+		return 0, fmt.Errorf("could not parse integer part: %w", err)
+	}
+
+	decimal, err := minutesToDegrees(minutesRaw)
+	if err != nil {
+		return 0, fmt.Errorf("could not parse decimal part: %w", err)
+	}
+
+	return integer + decimal, nil
+}
+
+// minutesToDegrees converts minutes to decimal part of a degree.
+func minutesToDegrees(raw []byte) (float64, error) {
+	minutes, err := strconv.ParseFloat(string(raw), 64)
+	if err != nil {
+		return 0, err
+	}
+
+	return minutes / 60, nil
+}