Spacebar as group separator

[tomasbaran]

It would be really great to also include a as a group separator.
e.g. 100000 -> 100 000

Currently, we have to do this to make it happen: https://stackoverflow.com/questions/50133321/change-grouping-separator-in-numberformat-for-dart

[mosuem]

I suppose you want an easier way to define or customize a NumberFormat. I agree that having to set an unused string such as zz as a locale name seems a bit hacky.