[#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/column/util.go

@@ -0,0 +1,9 @@
+package locodecolumn
+
+func isDigit(sym uint8) bool {
+	return sym >= '0' && sym <= '9'
+}
+
+func isUpperAlpha(sym uint8) bool {
+	return sym >= 'A' && sym <= 'Z'
+}