pv-wrap: Temporarily provide /run/host/container-runtime
SDL 2.26.x doesn't detect non-Flatpak, non-Snap sandboxes correctly (a regression in 2.25.1, specifically commit e8cb4da7 "Add utility function to detect if SDL is inside a sandbox") because the path it looks for was unintentionally changed from the intended /run/host/container-manager (from systemd's Container Interface document) to /run/host/container-runtime.
Until we get the fixed SDL deployed to all branches, we can easily work around this by having pressure-vessel provide both paths.
steamrt/tasks#234
Not tested yet, but I think this will work. If we land this and do a pressure-vessel release, then overwriting pressure-vessel/ with the one that has this change becomes an option as a hotfix for game controller hotplug on Proton and Steam Deck, which might be a minimal-risk thing to apply to the production branch.