Feature Request - Add currency named formats with 4 decimals

[Dawid]

I prefer to use value_format_name any day over writing custom formats that can be mistakenly typed diffferently in multiple places. 

However, one thing I’m missing is: usd_4, eur_4, gbp_4, mostly to show currency exchange rates that sometimes need this kind of precision.

I was trying to achieve it via value_format with #,###.0000 but it tells me this is not valid