♻️ Refactor Packaging and CI

[burgholzer]

Description

This PR brings a major refactoring for the overall Python packaging as well as the CI employed in the project.

Packaging

We are (finally) moving away from setuptools and towards modern scikit-build-core (https://scikit-build-core.readthedocs.io/) This brings many advantages such as

• truly editable installs that also include the C++ part; this implies incredibly fast rebuilds that can be further improved by installing ccache.
• completely eliminates the setup.py (and the MANIFEST.in) file and all custom build code that was required previously.

As part of this change, we adopt the established best practice of a src-layout for the Python package. This implies that the Python package no longer lives in the main package directory, but is moved to src/mqt/.... This avoids several pitfalls when working with Python packages and makes the overall handling way easier.

This also means there is no direct build-time dependency on cmake and ninja anymore as this is automatically handled by scikit-build-core on demand.

As part of this rewrite, several nox sessions are also updated

CI

MQT Core has introduced reusable workflows in

• https://github.com/cda-tum/mqt-core/pull/396

These have been further refined in

• https://github.com/cda-tum/mqt-core/pull/407

Overall, this allows to

• remove almost all workflow files of this repository
• eliminate a lot of maintenance required in this repository to keep up with the latest best practices
• rely on dependabot for workflow updates once MQT Core has settled enough so that it follows proper versioning and we can use tags for the workflows here instead of @main

while at the same time:

• having automatic change detection and only triggering jobs that are really necessary; with a single pass check that can be used for branch protection
• setting up ccache for all supported workflow jobs which greatly improves compilation times
• setting up mold as a better linker under linux
• splitting jobs into as many subjobs as possible and feasible to distribute work
• automatically creating wheels for all supported platforms (including exotic platforms that need emulation) and Python versions using PyPI trusted publishing
• enabling automatic retries for flaky jobs such as MSVC builds or coverage uploads
• enabling automatic build parallelization via using Ninja wherever suitable
• running an automatic workflow using the minimal versiosn for all Python dependencies to guarantee compatibility

As a nice side effect, the new CI runs have revealed a bug in the permutation handling of the ZX checker that has subsequently been resolved.

Checklist:

• [x] The pull request only contains commits that are related to it.
• [x] I have added appropriate tests and documentation.
• [x] I have made sure that all CI jobs on GitHub pass.
• [x] The pull request introduces no new warnings and follows the project's style guidelines.

[github-advanced-security[bot]]

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[codecov[bot]]

Codecov Report

Merging #301 (67c7576) into main (1e3f721) will decrease coverage by 0.1%. The diff coverage is 100.0%.

@@           Coverage Diff           @@
##            main    #301     +/-   ##
=======================================
- Coverage   96.1%   96.0%   -0.1%     
=======================================
  Files         34      34             
  Lines       1719    1726      +7     
  Branches     208     210      +2     
=======================================
+ Hits        1652    1658      +6     
- Misses        67      68      +1     

Flag	Coverage Δ
cpp	95.7% <100.0%> (-0.1%)	:arrow_down:
python	97.2% <100.0%> (+<0.1%)	:arrow_up:

Files Changed	Coverage Δ
...dd/applicationscheme/GateCostApplicationScheme.cpp	94.8% <ø> (ø)
src/mqt/qcec/compilation_flow_profiles.py	97.4% <ø> (ø)
src/mqt/qcec/configuration.py	100.0% <ø> (ø)
src/checker/zx/ZXChecker.cpp	99.3% <100.0%> (-0.7%)	:arrow_down:
src/mqt/qcec/__init__.py	100.0% <100.0%> (ø)
src/mqt/qcec/parameterized.py	94.8% <100.0%> (ø)
src/mqt/qcec/verify.py	100.0% <100.0%> (ø)
src/mqt/qcec/verify_compilation_flow.py	100.0% <100.0%> (ø)

... and 3 files with indirect coverage changes

[github-actions[bot]]

Cpp-Linter Report :heavy_check_mark:

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