[Photos Flatpak] Support Wayland by default

[MineGene]

By default it seems the Flatpak uses x11 by default.

It would be nice to support the Wayland and fallback to x11 in the absence of it being available.

I managed to get it working under Wayland on Bluefin with the following exec parameters: /usr/bin/flatpak run --branch=stable --arch=x86_64 --command=run.sh --file-forwarding io.ente.photos @@u --enable-features=UseOzonePlatform --ozone-platform=wayland %U @@

Additionally I had to set env vars as following: WAYLAND_DISPLAY=wayland-0