Convert static methods to scopes

[gdebrauwer]

Converting the whereLocale() / whereLocales() static methods to scopes makes it possible to use them on existing queries instead of being required to use them as the first method

[freekmurze]

I like the proposal, but this is a breaking change. Could you re-add the old methods and add a @deprecated annotation above the function? We'll remove these old methods in the next major version of the package.

[freekmurze]

Thanks!