Add custom build environment

It order to enable MPI backend we need MPI libraries in our build environment
To make mpi aware build environment we use official pytorch/manylinux2_28-builder
as a base and install EFA/openmpi

Usage: make -C poolside/build_env build

poolside/build_env/Dockerfile

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+ARG IMAGE_NAME=pytorch/manylinux2_28-builder
+ARG IMAGE_BASE_TAG="cuda12.6-main"
+
+FROM ${IMAGE_NAME}:${IMAGE_BASE_TAG}
+
+#
+# Build trick #1
+# Almalinux is not officially supported by aws-efa-installer
+# but in a nutshell it is just an EL8 based distro, so we mimic to RockyLinux
+#
+# Build trick #2 (workaround for FindMPI.cmake bug)
+# By unknown reason FindMPI.cmake[1] try to detect MPI library presence
+# by lookup  mpi-${LANG} PKG, but openmpi standard is known to have
+# ompi-${LANG} pkg naming convention. So we have to manually create a symlinks
+# and privided explicit PKG_CONFIG_PATH 
+#
+#Footnotes
+#[1]https://github.com/Kitware/CMake/blob/master/Modules/FindMPI.cmake#L1592-L1597
+# Install EFA libs
+ARG AWS_EFA_INSTALLER=1.34.0
+RUN mkdir -p /tmp/efa \
+    && cd /tmp/efa \
+    && curl -sSL https://efa-installer.amazonaws.com/aws-efa-installer-${AWS_EFA_INSTALLER}.tar.gz | tar -xz \
+    && cd aws-efa-installer \
+    && cp /etc/os-release /etc/os-release.orig \
+    && sed -i 's/AlmaLinux/Rocky Linux/g' /etc/os-release \
+    && ./efa_installer.sh -y --skip-kmod --no-verify --enable-gdr \
+    && mv /etc/os-release.orig /etc/os-release \
+    && echo "/opt/amazon/openmpi/lib64" >> /etc/ld.so.conf.d/000_ompi.conf \
+    \
+    && pushd /opt/amazon/openmpi/lib64/pkgconfig \
+    && ln -s ompi.pc mpi.pc \
+    && ln -s ompi-c.pc mpi-c.pc \
+    && ln -s ompi-cxx.pc mpi-cxx.pc \
+    && popd \
+    && ldconfig \
+    && cd / \
+    && rm -rf /tmp/efa
+
+ENV PATH=$PATH:/opt/amazon/openmpi/bin
+ENV LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/opt/amazon/openmpi/lib64
+ENV PKG_CONFIG_PATH=/opt/amazon/openmpi/lib64/pkgconfig

poolside/build_env/Makefile

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+# Image base
+IMAGE_NAME ?= 939990436136.dkr.ecr.us-east-2.amazonaws.com/pytorch/manylinux2_28-builder
+IMAGE_BASE_TAG  ?= cuda12.6-main
+
+# Build dependencies
+AWS_EFA_INSTALLER_VER ?=1.34.0
+
+# Export options
+EXPORT_PATH ?= ..
+ZSTD_COMPRESS_OPTIONS ?= --ultra -22
+
+# Out output options
+IMAGE_TAG=${IMAGE_BASE_TAG}-efa${AWS_EFA_INSTALLER_VER}
+
+build:
+	docker build --progress plain --rm \
+		--tag "${IMAGE_NAME}:${IMAGE_TAG}" \
+		--build-arg IMAGE_NAME="${IMAGE_NAME}" \
+		--build-arg IMAGE_BASE_TAG="${IMAGE_BASE_TAG}" \
+		--build-arg AWS_EFA_INSTALLER="${AWS_EFA_INSTALLER_VER}" \
+		-f Dockerfile ..
+
+tar-img:
+	docker save \
+		"${IMAGE_NAME}:${IMAGE_TAG}"  | \
+		zstdmt ${ZSTD_COMPRESS_OPTIONS} -v -f -o ${EXPORT_PATH}/${IMAGE_NAME}-${IMAGE_TAG}.tar.zst
+
+push:
+	docker push "${IMAGE_NAME}:${IMAGE_TAG}"