Use more environment variables for OS detection

[Brycey92]

Description

I've replaced a ton of preprocessor OS detections in rawdraw, cnfa, and the swadge repo. However, I didn't replace all of them, especially where it looked like the author was intentionally not using all possible environment variable names (that they knew of) to detect a certain OS.

This fixes an issue where make usbflash fails to work on Windows with the current toolchain.

Respective PRs for the submodules can be found here for rawdraw and cnfa.

Test Instructions

As a warning, I've only tested this in a Windows Cygwin environment, so other environments and OSes still need to be tested.

Readiness Checklist

make format failed with the following error:

YAML:14:3: error: unexpected scalar
  Kind: Always
  ^

As for compile warnings, too many have slipped past into this repo for me to be able to easily check for new ones. I can check by hand, if required.

• [ ] I have run make format to format the changes
• [ ] I have compiled the firmware and the changes have no warnings
• [ ] I have compiled the emulator and the changes have no warnings
• [x] I have run make cppcheck and checked that cppcheck_result.txt has no warnings for the changes
• [x] I have added doxygen comments to any code used by more than one Swadge mode. This includes /*! \file comments with Design Philosophy, Usage, and Example sections for new headers.
• [x] I have run make docs and checked that doxy_warnings.txt has no warnings for the new code

[AEFeinstein]

You know, we also have OS detection in the makefile and we could use it to append something consistent to DEFINES_LIST for each OS rather than check a dozen things a dozen places. What we have:

################################################################################
# What OS we're compiling on
################################################################################

ifeq ($(OS),Windows_NT)
    HOST_OS = Windows
else
    UNAME_S := $(shell uname -s)
    ifeq ($(UNAME_S),Linux)
        HOST_OS = Linux
    else ifeq ($(UNAME_S),Darwin)
        HOST_OS = Darwin
    endif
endif

What we could add:

ifeq ($(HOST_OS),Windows)
    DEFINES_LIST += WINDOWS=1
else ifeq ($(HOST_OS),Linux)
    DEFINES_LIST += __linux__=1
else ifeq ($(UNAME_S),Darwin)
    DEFINES_LIST += __APPLE__=1
endif

Admittedly this would only be for the emulator, not the tools folder.