Add install scripts (Flatpak) (#471)

Co-authored-by: ReenigneArcher <42013603+ReenigneArcher@users.noreply.github.com>

packaging/linux/flatpak/dev.lizardbyte.sunshine.yml

@@ -208,3 +208,7 @@ modules:
       - sed -r -z -i -e
         's/("((do)|(undo)|(cmd)|(detached))"\s*:\s*\[?\n*\s*")(.*")/\1flatpak-spawn --host \7/gm'
         /app/share/sunshine/apps.json
+      - sed -i
+        's%/app/bin/sunshine%flatpak run dev.lizardbyte.sunshine\nExecStop=flatpak kill dev.lizardbyte.sunshine%g'
+        /app/share/sunshine/systemd/user/sunshine.service
+      - install -D $FLATPAK_BUILDER_BUILDDIR/packaging/linux/flatpak/scripts/* /app/bin