Gt: `fmt_currency()` should have the option to do foreign exchange conversions

[MadhulikaTanuboddi]

I was expecting that fmt_currency function would do a literal currency conversion. I noticed that this function would just add the respective country currency symbol to currency column but still keep the same number.

It would be nice to have this feature added if possible

for ex:
check the snapshots below. Using euro and USD as currency options, the numbers in the table are same except that the currency symbol is changed

[charlesatkinson2000]

This would be pretty interesting. I suppose that these conversions would have to be tied to some sort of date or datetime (from a column or manually specified) or range of dates (for averaging).