Add FixedPointOperand blanket implementation (#14634)

* bound `Balance` to `FixedPointOperand`

* ".git/.scripts/commands/fmt/fmt.sh"

* clean up code

* Apply suggestions from code review

Co-authored-by: Gavin Wood <gavin@parity.io>

* wip

* add blanket `FixedPointOperand` impl

* update nis CurrencyBalance

* remove CheckedNeg bound

---------

Co-authored-by: command-bot <>
Co-authored-by: Gavin Wood <gavin@parity.io>

substrate/primitives/arithmetic/src/fixed_point.rs

@@ -52,16 +52,18 @@ pub trait FixedPointOperand:
 {
 }
 
-impl FixedPointOperand for i128 {}
-impl FixedPointOperand for u128 {}
-impl FixedPointOperand for i64 {}
-impl FixedPointOperand for u64 {}
-impl FixedPointOperand for i32 {}
-impl FixedPointOperand for u32 {}
-impl FixedPointOperand for i16 {}
-impl FixedPointOperand for u16 {}
-impl FixedPointOperand for i8 {}
-impl FixedPointOperand for u8 {}
+impl<T> FixedPointOperand for T where
+	T: Copy
+		+ Clone
+		+ Bounded
+		+ Zero
+		+ Saturating
+		+ PartialOrd
+		+ UniqueSaturatedInto<u128>
+		+ TryFrom<u128>
+		+ CheckedNeg
+{
+}
 
 /// Something that implements a decimal fixed point number.
 ///