Python script to build installers and wheels for all platforms and Python versions

• A Python script is added to build the installers and Python wheels for all platforms (Linux, MacOS, Windows) and all Python versions (3.8–3.11), and automatically produce the artifacts; see devtools/deploy/multipy/build_multipy.py.

  The script is tested successfully on all platforms, and should be only executed via a pipeline trigger mechanism, as the build process is very resource-consuming.

  As the script has all the details of the build mechanism, it is possible to use the script instead of the statements in the GitLab-CI YAML file .gitlab-ci.yml to avoid duplication. Such a decision deserves some discussion.

• The Linux shell script, devtools/deploy/linux/my_pypack_linux.sh, is extended to 'repair' the Python wheel and produce a 'manylinux' wheel according to PEP 599 using the auditwheel package. The paths for artifacts are corrected accordingly.

• Some build scripts are slightly improved.

Related to #223, #598 (closed) and #157