Added a docker image to build www.videolan.org.

website-debian/Dockerfile

+FROM debian:bullseye-20230208-slim
+
+MAINTAINER VideoLAN roots <roots@videolan.org>
+
+ENV IMAGE_DATE=202302281650
+
+# If someone wants to use VideoLAN docker images on a local machine and does
+# not want to be disturbed by the videolan user, we should not take an uid/gid
+# in the user range of main distributions, which means:
+# - Debian based: <1000
+# - RPM based: <500 (CentOS, RedHat, etc.)
+ARG VIDEOLAN_UID=499
+
+RUN addgroup --quiet --gid ${VIDEOLAN_UID} videolan && \
+    adduser --quiet --uid ${VIDEOLAN_UID} --ingroup videolan videolan && \
+    usermod --append --groups video videolan && \
+    echo "videolan:videolan" | chpasswd && \
+    apt-get update && \
+    apt-get install -y --no-install-suggests --no-install-recommends \
+        make php-cgi php-curl php-gd php-intl php-mbstring php-json \
+        php-opcache php-pgsql php-readline php-xml git ca-certificates sassc \
+        gettext locales-all yui-compressor \
+    && apt-get clean -y && rm -rf /var/lib/apt/lists/*
+
+USER videolan