Sets vendor and product IDs, defaults to the prior default values.
This is needed for some games to be able to correctly identify the virtual devices since not all games support device indexes.
Reviewed-on: https://codeberg.org/annabunches/joyful/pulls/10
This also moves validation into the parsing process and refactors a bunch of code related to the config.
Reviewed-on: #18
Co-authored-by: Anna Rose Wiggins <annabunches@gmail.com>
Co-committed-by: Anna Rose Wiggins <annabunches@gmail.com>
