feat: significant figures

[privatenumber]

Feature description

Would like to set significant figures on the output value.

So, for example, 1 KB could be outputted as 1.00 KB.

Use case

When I have the values in a right-aligned table, the numbers that end with a 0 are truncated and have different string lengths:

[ouuan]

The pad option is not exactly significant figures. See https://en.wikipedia.org/wiki/Significant_figures#Rounding_to_significant_figures

[avoidwork]

I know; significant figures doesn't matter to me for this lib. PR or it'll never land.

[ouuan]

I think significant figures do matter. Let's say you want to see 1.34GB instead of 1GB but don't want to see 724.16MB instead of 724MB. For instance, GitHub Releases is using significant figures:

If you still think it doesn't matter, I could try drafting a PR.

[avoidwork]

Please do, features are driven by other people at this point.