Reduce exposure to Posix APIs

Previously the code had several references to functions that only exist
on a Posix compliant OS which caused problems when bringing the code up
on Windows.  Now the Posix APIs are only used in main/MockDefaults.c to
implement new Console_* abstractions when not building for WIN32.

Changes include:
* Added Console_* APIs which are used in StandardIComm to read/write
  stdin/stdout without using OS specific APIs directly.  The actual
  implementation of these abstractions can be found in
  main/MockDefaults.c
* Deleted mockFileIo files as most of the Posix routines being mocked
  are no longer in use.  The fgets() mock (which is actually a standard
  C function and not Posix) was moved to the FileFailureInject module.
* Deleted mockSock files as these Posix specific routines are no longer
  in use from the core code being unit tested.
* Added a mockConsole module so that StandardIComm could be unit tested
  via the new Console_* abstraction rather than Posix specific mocks.