Improved integer and floating point formatted() methods.

- [IntegerFormatStyle] I removed the trapping conversion to `Int`. IntegerFormatStyle can format big integers since (swiftlang#262).
- [FloatingPointFormatStyle] I removed the rounding conversion to `Double`. `formatted()` now does whatever `format(_:)` does.
- [Decimal.FormatStyle] N/A (there were no conversions here).

Sources/FoundationInternationalization/Formatting/Number/BinaryFloatingPoint+FormatStyle.swift

@@ -19,7 +19,7 @@ extension BinaryFloatingPoint {
 
     /// Format `self` with `FloatingPointFormatStyle()`.
     public func formatted() -> String {
-        FloatingPointFormatStyle().format(Double(self))
+        FloatingPointFormatStyle().format(self)
     }
 
     /// Format `self` with the given format.

Sources/FoundationInternationalization/Formatting/Number/BinaryInteger+FormatStyle.swift

@@ -25,7 +25,7 @@ extension BinaryInteger {
 
     /// Format `self` using `IntegerFormatStyle()`
     public func formatted() -> String {
-        IntegerFormatStyle().format(Int(self))
+        IntegerFormatStyle().format(self)
     }
 
     /// Format `self` with the given format.