build(docker/backend): make FROM image and tag configurable by build-arg

use docker.io haskell image per default as build-arg, and later use fraport-internal args for pipeline

docker/backend/Dockerfile

@@ -1,4 +1,20 @@
-FROM fradrive/backend:8.10.4
+ARG FROM_IMG=docker.io/library/haskell
+ARG FROM_TAG=8.10.4
+FROM ${HASKELL_IMG}:${FROM_TAG}
+
+ENV LANG=de_DE.UTF-8
+
+# compile-time dependencies
+RUN apt-get -y update && apt-get install -y libpq-dev libsodium-dev
+# RUN apt-get -y update && apt-get -y install llvm
+# RUN apt-get -y update && apt-get -y install g++ libghc-zlib-dev libpq-dev libsodium-dev pkg-config
+# RUN apt-get -y update && DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tzdata
+RUN apt-get -y update && apt-get install -y --no-install-recommends locales locales-all
+
+# run-time dependencies for uniworx binary
+RUN apt-get -y update && apt-get -y install fonts-roboto
+# RUN apt-get -y update && apt-get -y install pdftk
+RUN apt-get -y update && apt-get -y install texlive-latex-recommended texlive-luatex texlive-plain-generic texlive-lang-german texlive-lang-english
 
 # locally these two should be identical, so that compilation results are written out into the file dir.
 # in CI-pipelines these two should be different, so that the container caches the compilation results.