Add libgudev to Platform/Sdk
Recently libudev
was added in freedesktop Platform/Sdk as it's quite common dependency for apps in flathub. libgudev
is its gnome/gtk companion which is additionally needed by some gnome/gtk apps.
Providing it in flatpak runtime would save those apps from bundling it themselves and finally make ancient udev from shared-modules obsolete.
libgudev is already available in the project so it just matter of exposing it in flatpak runtime.