Add `set -euxo pipefail` to all HereDocs in the Dockerfile

[RmStorm]

The HereDocs are basically shell scripts but the standard shell script precautions are not being taken. Me and a colleague encountered a quite strange failure mode this morning trying to run the image. Removing the first couple HereDocs and just using a lot of RUN commands solved it but adding set -euxo pipefail to every HereDoc should also make the Dockerfile more robust..

[coderbyheart]

Good idea!