feat: Add workaround for Sunshine to set correct caps for KMS

Containerfile

@@ -428,6 +428,7 @@ RUN /tmp/image-info.sh && \
     systemctl disable rpm-ostreed-automatic.timer && \
     systemctl enable ublue-update.timer && \
     systemctl enable gamescope-workaround.service && \
+    systemctl enable sunshine-workaround.service && \
     systemctl enable waydroid-workaround.service && \
     systemctl enable bazzite-hardware-setup.service && \
     systemctl enable tailscaled.service && \

system_files/desktop/shared/usr/lib/systemd/system/sunshine-workaround.service

@@ -0,0 +1,20 @@
+[Unit]
+Description=Workaround sunshine not having the correct caps
+ConditionFileIsExecutable=/usr/bin/sunshine
+After=local-fs.target
+
+[Service]
+Type=oneshot
+# Copy if it doesn't exist
+ExecStartPre=/usr/bin/bash -c "[ -x /usr/local/bin/.sunshine ] || /usr/bin/cp /usr/bin/sunshine /usr/local/bin/.sunshine"
+# This is faster than using .mount unit. Also allows for the previous line/cleanup
+ExecStartPre=/usr/bin/mount --bind /usr/local/bin/.sunshine /usr/bin/sunshine
+# Fix caps
+ExecStart=/usr/sbin/setcap cap_sys_admin+p /usr/bin/sunshine
+# Clean-up after ourselves
+ExecStop=/usr/bin/umount /usr/bin/sunshine
+ExecStop=/usr/bin/rm /usr/local/bin/.sunshine
+RemainAfterExit=yes
+
+[Install]
+WantedBy=multi-user.target

system_files/desktop/shared/usr/lib/tmpfiles.d/sunshine-workaround.conf

@@ -0,0 +1 @@
+C /usr/local/bin/.sunshine - - - - /usr/bin/sunshine