Move the protobuf source into its own dir in the repo root

The protobuf source file is used by more than just the C++ code,
so let's move it into its own location for consistency and discoverability

docker/backend/Dockerfile

@@ -12,6 +12,7 @@ WORKDIR /home/pi/piscsi
 COPY --chown=pi:pi easyinstall.sh .
 COPY --chown=pi:pi cpp cpp
 COPY --chown=pi:pi doc doc
+COPY --chown=pi:pi proto proto
 RUN ./easyinstall.sh --run_choice=16 --cores=`nproc`
 
 FROM debian:bullseye-slim AS runner

docker/web/Dockerfile

@@ -26,7 +26,7 @@ WORKDIR /home/pi/piscsi
 
 COPY --chown=pi:pi easyinstall.sh .
 COPY --chown=pi:pi os_integration os_integration
-COPY --chown=pi:pi cpp/piscsi_interface.proto cpp/piscsi_interface.proto
+COPY --chown=pi:pi proto proto
 COPY --chown=pi:pi python/web python/web
 COPY --chown=pi:pi python/common python/common
 

docker/web/web_start_wrapper.sh

@@ -3,9 +3,9 @@
 if ! [[ -f "/home/pi/piscsi/python/common/src/piscsi_interface_pb2.py" ]]; then
     # Build piscsi_interface_pb2.py with the protobuf compiler
     protoc \
-        -I=/home/pi/piscsi/cpp \
         --python_out=/home/pi/piscsi/python/common/src \
-        piscsi_interface.proto
+        --proto_path=/home/pi/piscsi/proto \
+        /home/pi/piscsi/proto/piscsi_interface.proto
 fi
 
 # Start Nginx service