Use meson-python instead of setuptools

[awvwgk]

Currently the Python bindings can be built with setuptools or meson, the latter is preferred since we have more control with meson over the build environment. For building the Python wheels we therefore use meson-python a PEP517 compliant build system wrapping meson.

Some upstream issues with preferably should be resolved first:

• possibility to include subprojects in sdist: https://github.com/FFY00/meson-python/issues/59
• support for editable / development installations: https://github.com/FFY00/meson-python/issues/47

From our side we need to do some testing on MacOS, Windows and *BSD.

• successful build on MacOS/x86_64
• successful build on Windows
• successful build on *BSD