feat: use Intl.PluralRules for plural keys

[vladimirfilosof]

Now plural format can be:

{
	"one": "{{count}} thing",
	"zero": "Nothing found",
	"other": "{{count}} things",
}

[dgaponov]

I did a little refactoring. You can watch and check PR from me #44
The main suggestion is to put the logic of the plural forms in a separate file.