Use `~/Library/Application Support/DevAuth` for the config directory on macOS

[caoimhebyrne]

Since XDG_CONFIG_HOME is used on Linux, let's show macOS some love too? :thinking:

This does introduce a breaking change for macOS users, though. They will need to migrate their configuration from .devauth to ~/Library/Application Support/DevAuth for it to be recognized, which can be done quite simply:

# Create the DevAuth configuration directory
mkdir ~/Library/Application Support/DevAuth

# Copy the required configuration files to the new directory
cp ~/.devauth/* ~/Library/Application\ Support/DevAuth

# (Optional) remove ~/.devauth
rm -rf ~/.devauth

I'm unsure if DevAuth should perform a migration here. If you don't think a migration is worth it: logging a warning whenever DevAuth is launched without a ~/Library/Application Support/DevAuth directory, but with a ~/.devauth directory, would make sense.

[caoimhebyrne]

Also, I will not add %appdata% on Windows, nobody uses Windows anyways so :P