Add Dockerfile including preCICE installation

[BenjaminRodenberg]

This PR contributes a Dockerfile for installing preCICE on top of ci-ubuntu-2004.

[BenjaminRodenberg]

Important note: test_base was failing for me when I tried to build the image. I could not find an obvious reason, but will try to investigate. However, I did not run into further problems downstream when using this image (see precice/python-bindings#67).

[BenjaminRodenberg]

7dec86f fixes the problem with the tests by using a non-root user. Ready for review.

[fsimonis]

What is the use-case for this image?

As we discussed, there will soon be a preCICE docker image which will be updated with every release.
Doesn't it fulfil your requirements?

[BenjaminRodenberg]

on the use-case

The main use-case is the CI pipeline for the python-bindings. See precice/python-bindings#67.

on the requirements

I first tried to use https://github.com/precice/systemtests/blob/develop/precice/Dockerfile.Ubuntu2004.home for my test. However, here, curl and python3 was missing which is provided with https://github.com/precice/ci-images/blob/master/ci-ubuntu-2004.dockerfile. That's the main reason why I decided to create a new image based on ci-ubuntu-2004.

[fsimonis]

This PR is superseded by precice/precice#910