Start to make use of Flatpak 1.10.1 features
-
launch: Update FlatpakSpawnFlags from Flatpak 1.10.0 (interface v5)
-
launch: Sync minor improvements from flatpak-xdg-utils
-
launch: Use unset-env option for subsandbox API >= v5
This was added in Flatpak 1.10.0.
-
launch: Add --share-pids option
We'll need this if we want to put a Flatpak subsandbox in our process ID namespace, so that Steam and the game can use process-ID-based IPC.
Needed for !203 (merged).