Swift MMIO 0.0.1

Swift MMIO initial release.

Additions

• Introduces @RegisterBank and @RegisterBank(offset:) macros, enabling you
  to define register groups directly in Swift code. #2
• Introduces @Register macro and bit field macros (@Reserved, @ReadWrite,
  @ReadOnly, @WriteOnly) for declaring registers composed of bit fields. Bit
  field macros take a range parameter which describes the subset of bits they
  reference (e.g., @ReadWrite(bits: 3..<7)). #4
• Enhances bit field macros to support discontiguous bit fields. They now accept
  a variadic list of bit ranges and automatically handle scattering/gathering
  from the relevant bits (e.g., @ReadWrite(bits: 3..<7, 10..<12)). #10
• Enhances bit field macros with type projections via a new as: parameter.
  Projections allow you to operation on bit fields using strong types instead of
  raw integers (e.g. @ReadWrite(bits: 3..<7, as: A.self)) #27
• Enhances registers with support for interposing reads and writes when
  compiling with FEATURE_INTERPOSABLE. You can use interposers to unit test
  drivers. This feature is enabled when building with the
  SWIFT_MMIO_FEATURE_INTERPOSABLE environment variable defined. #31

The 0.0.1 release includes contributions from @rauhul. Thank you!