✨ switch to mqt-core Python package

[burgholzer]

Description

This PR switches the project to use the newly developed mqt-core Python package.
Any Python package build will only require the mqt-core package as a build and runtime dependency and won't have to rely on fetched version of mqt-core any more.
Any regular C++ build will still use the FetchContent CMake module.

The change brings a range of advantages:

• Uses the new load function of mqt-core that allows to load any supported circuit format as input and has better handling for Qiskit QuantumCircuit objects.
• Simplifies the interfaces of the DDSIM Python bindings
• Allows OpenQASM3 as an input format.

Checklist:

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

[codecov]

Codecov Report

Attention: Patch coverage is 90.62500% with 3 lines in your changes missing coverage. Please review.

Project coverage is 92.4%. Comparing base (31a7ccc) to head (bb7ffd3).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/mqt/ddsim/pathqasmsimulator.py	57.1%	3 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #336     +/-   ##
=======================================
+ Coverage   92.3%   92.4%   +0.1%     
=======================================
  Files         37      37             
  Lines       2721    2739     +18     
  Branches     305     304      -1     
=======================================
+ Hits        2513    2533     +20     
+ Misses       208     206      -2     

Flag	Coverage Δ
cpp	94.0% <ø> (-0.1%)	⬇️
python	88.1% <90.6%> (+0.7%)	⬆️

Files with missing lines	Coverage Δ
src/mqt/ddsim/__init__.py	100.0% <100.0%> (ø)
src/mqt/ddsim/deterministicnoisesimulator.py	100.0% <100.0%> (ø)
src/mqt/ddsim/hybridqasmsimulator.py	91.2% <100.0%> (+0.3%)	⬆️
src/mqt/ddsim/primitives/estimator.py	93.4% <100.0%> (+0.1%)	⬆️
src/mqt/ddsim/qasmsimulator.py	98.8% <100.0%> (+<0.1%)	⬆️
src/mqt/ddsim/stochasticnoisesimulator.py	100.0% <100.0%> (ø)
src/mqt/ddsim/unitarysimulator.py	89.3% <100.0%> (+0.3%)	⬆️
src/mqt/ddsim/pathqasmsimulator.py	53.2% <57.1%> (+1.8%)	⬆️

... and 3 files with indirect coverage changes