(PUP-2382) Create FFI typedefs for Win32 API

• Add new file windows/api_types to contain global FFI typedefs that can be reused wherever we attach_function for FFI
• Replace existing function definitions with new Win32 API style typedefs such as :dword, :lpcstr, :handle, etc
• Fix some API definitions that were using incorrect FFI typedefs such as :ulong and :long. In FFI, these typedefs are platform specific and will vary in size. On Windows, these are fixed width. New Win32 typedefs of :win32_ulong and :win32_long were added to accommodate these in function definitions.
• Fix replace_file by passing FFI::Pointer::NULL to match it's updated definition.
• Where applicable, modify FFI::MemoryPointer.new to use the Win32 typedef being created, so .new(:dword, 1) instead of .new(:uint, 1)
• Prefix each attach_function with an ffi_lib for the dll it's actually loaded in.
• Add missing documentation / links where helpful.

Paired-with: Rob Reynolds <rob@puppetlabs.com>