Log whether we are running as an AppImage

[aidalgol]

Similar to the log message,

We are [not] running in a Flatpak container

Add a log message for AppImage,

We are [not] running from an AppImage

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Use the following Checklist if you have changed something on the Backend or Frontend:

• Tested the feature and it's working on a current and clean install.
• Tested the main App features and they are still working on a current and clean install. (Login, Install, Play, Uninstall, Move games, etc.)
• Created / Updated Tests (If necessary)
• Created / Updated documentation (If necessary)

[arielj]

I wonder if we can make all the steamdeck/flatpak/appimage block conditional to show up only for linux? it adds noise on macos and windows

[CommandMC]

Note: The Steam Deck check is intentionally not Linux-specific (by detecting hardware details instead), that one can stay IMO. Yes, it's unlikely that anyone will install Windows on their Deck & use Heroic, but still; whether a device is a Steam Deck has nothing to do with the device's OS

Either way, the actual change here looks good to me