Copy UBT from minimal to conan stage if present

See adamrehn#281 and adamrehn/conan-ue4cli#20

This also requires adamrehn/conan-ue4cli#15 to make `ue4 conan generate` work on UE5.

Author: Justin Lewis Salmon

src/ue4docker/dockerfiles/ue4-full/linux/Dockerfile

@@ -19,6 +19,14 @@ RUN pip3 install --upgrade pip setuptools wheel
 RUN pip3 install "$CONAN_VERSION" "$UE4CLI_VERSION" "$CONAN_UE4CLI_VERSION"
 USER ue4
 
+# Copy in UBT from minimal image, if present (required for `ue4 conan generate` to work on UE5)
+ARG UBT_DIR="/home/ue4/UnrealEngine/Engine/Binaries/DotNET"
+{% if combine %}
+COPY --from=minimal --chown=ue4:ue4 $UBT_DIR/UnrealBuildToo[l] $UBT_DIR/UnrealBuildTool
+{% else %}
+COPY --from=${NAMESPACE}/ue4-minimal:${TAG}-${PREREQS_TAG} --chown=ue4:ue4 $UBT_DIR/UnrealBuildToo[l] $UBT_DIR/UnrealBuildTool
+{% endif %}
+
 # Extract the third-party library details from UBT
 RUN ue4 setroot /home/ue4/UnrealEngine
 RUN ue4 conan generate