Add Python to the build images

See merge request docker-images/gr-build-images!33

ICU needs Python for some generation tasks, so add it to the build
images.

Add a Docker image for `clang-tidy` checks

See merge request docker-images/gr-build-images!32

Remove Qt5 CMake Config files in MinGW images

See merge request docker-images/gr-build-images!31

The Qt5 config files for CMake are not written to work with MinGW.
Instead, use the CMake find module of the Qt5 runtime archive.

Upgrade the Emscripten Ubuntu image to 20.04

See merge request docker-images/gr-build-images!30

Upgrade the underlying operating system for a newer CMake version which
is necessary to compile Xerces-C++.

Add missing `which` in Arch images

See merge request docker-images/gr-build-images!29

Without `which`, the GR `Preflight` script does not work correctly.

Use Debian bookworm instead of sid for code-style-check image

See merge request docker-images/gr-build-images!28

Use virtual env in code-style-check image

See merge request docker-images/gr-build-images!27

deploy-to-obs: Use rockylinux 8 repositories

See merge request docker-images/gr-build-images!26

Co-authored-by: Florian Rhiem <f.rhiem@fz-juelich.de>

Update images to support C++17

See merge request docker-images/gr-build-images!25

Otherwise, internal images cannot be used in the build process.

Deploy to obs (update)

See merge request docker-images/gr-build-images!24

Switch to rockylinux 8 and clang-format 13

See merge request docker-images/gr-build-images!22

Add Qt6 to Arch images

See merge request docker-images/gr-build-images!21

Update the base system of Arch Linux images

See merge request docker-images/gr-build-images!20

The official Arch Linux DockerHub webpage recommends to always run a
full system update in Arch Linux containers (see
<https://hub.docker.com/_/archlinux>).

Remove no longer needed `docker:dind` service from `deploy-to-aur` job

See merge request docker-images/gr-build-images!19

Use iffdocker.fz-juelich.de as registry mirror for docker-in-docker

See merge request docker-images/gr-build-images!17