in persian formatter digits do not convert to persian digits

[haniehtarbiat]

when build formatter by language-strings/fa the text convert to persian language but the digits don't convert to persian digits.

[nmn]

I rely on pull request for translations. The language strings can take function that can convert digits to the right format. You're welcome to make a pull request. I will be happy to help. We basically just need a function to convert to Persian digits.

[nmn]

While this was not possible in the past, it might be possible to use the Intl module to convert the numbers to various locales now.

[nmn]

I've done this by using the Intl module when available in the latest release.

Looking for help verifying the results. (I'm not a native persian or arabic speaker or reader. As such I don't know if I've completely messed up the numbers in the RTL language)