Add parsing of formatted strings into integers

[bcmyers]

[zbraniecki]

that's likely a rabbit hole right here... Trying to guess which locale the number is in to distinguish between 1,000 being a float with int 1 and fraction 000 and an int 1000 with thousands separator, will be tricky.

And then, other numbering systems come in... In JS we decided not to do that for this reason.

[bcmyers]

I figured I would make the caller pass the locale explicitly, as I agree it's a rabbit hole otherwise.

Example...

let n = "1,000".parse_formatted::<_, u32>(&Locale:en)?;