Allow any range type as macro bits parameter

[rauhul]

Updates bit-field macros bits parameter to be generic over BinaryInteger RangeExpressions and adds an additional overload to enable the use of UnboundedRange.

Example new uses:

@Register(bitWidth: 32)
struct Example0 {
  @ReadWrite(bits: ...)
  var unbounded: Unbounded
}

@Register(bitWidth: 32)
struct Example1 {
  @ReadWrite(bits: ...16)
  var partialThrough: PartialThrough

  @ReadWrite(bits: 17...)
  var partialFrom: PartialFrom
}

@Register(bitWidth: 32)
struct Example2 {
  @ReadWrite(bits: ..<16)
  var partialUpTo: PartialUpTo

  @ReadWrite(bits: 16...31)
  var closed: Closed
}

Fixes #28