Add Non-Steam Game: Add Option to Find Artwork in EXE Directory

[sonic2kk]

Part of #906.

Overview

This PR adds a checkbox to the Add Non-Steam Game GUI which will look for artwork in the same folder as the game exe directory if it is named appropriately. If the user enables this option and DOES NOT select/pass any artwork (such as if they pass no artwork or if they only pass a banner image), we will search for artwork with a relevant name in the same folder as the game EXE.

This can be useful if you don't want to remember/enter long paths, or if your game already has icon.png or something along those lines in the game files, which is reasonably common. It's worth nothing as well that this option will respect the copy method option.

We will look for the following:

• Icon - Image files named icon
• Banner - Image files named hero
• Logo - Image files named logo
• Boxart - Image files named boxart
• Tenfoot - Image files named tenfoot

Any file format can be used as long as files sees that it is image data, however not all file formats may be recognised by Steam.

This feature is also available as a commandline flag with --auto-artwork.

Future Work

This is part of #906, so in future, this option can be used alongside an option to use SteamGridDB artwork, where there can be a fallback for any artwork that is not found (or if the call fails).

---

TODO:

• More testing
• Update langfiles
• Update wiki

[sonic2kk]

Testing looks good. Wiki will be updated on merge.

[sonic2kk]

Shit, forgot to update the helpscreen. Will do that when implementing the next part of #906.