Add extra (unsupported) container build arch's (#4524)

There was a PR (#4370) to add i686/i386 support for Vaultwarden.
That specific PR was not a viable way of adding this.

This PR adds extra architectures for Debian based containers which we
will not support by default. Those images will not be build and pushed
to our container registries.

Added the following architectures:
 - linux/386
 - linux/ppc64le
 - linux/s390x

Again, there will be no major support for these architectures, but it
will allow people who use these architectures to build a Debian based
binary more easily

docker/Dockerfile.debian

@@ -88,9 +88,17 @@ RUN mkdir -pv "${CARGO_HOME}" \
 RUN USER=root cargo new --bin /app
 WORKDIR /app
 
-# Environment variables for cargo across Debian and Alpine
+# Environment variables for Cargo on Debian based builds
+ARG ARCH_OPENSSL_LIB_DIR \
+    ARCH_OPENSSL_INCLUDE_DIR
+
 RUN source /env-cargo && \
     if xx-info is-cross ; then \
+        # Some special variables if needed to override some build paths
+        if [[ -n "${ARCH_OPENSSL_LIB_DIR}" && -n "${ARCH_OPENSSL_INCLUDE_DIR}" ]]; then \
+            echo "export $(echo "${CARGO_TARGET}" | tr '[:lower:]' '[:upper:]' | tr - _)_OPENSSL_LIB_DIR=${ARCH_OPENSSL_LIB_DIR}" >> /env-cargo && \
+            echo "export $(echo "${CARGO_TARGET}" | tr '[:lower:]' '[:upper:]' | tr - _)_OPENSSL_INCLUDE_DIR=${ARCH_OPENSSL_INCLUDE_DIR}" >> /env-cargo ; \
+        fi && \
         # We can't use xx-cargo since that uses clang, which doesn't work for our libraries.
         # Because of this we generate the needed environment variables here which we can load in the needed steps.
         echo "export CC_$(echo "${CARGO_TARGET}" | tr '[:upper:]' '[:lower:]' | tr - _)=/usr/bin/$(xx-info)-gcc" >> /env-cargo && \