📝 Add documentation for DD package

[burgholzer]

Description

This pull request includes extensive documentation updates for the DD Package of MQT Core.

It also adds two new convenience methods for statevector simulation and unitary construction to the mqt.core.dd Python module.

Fixes #814

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 95.45455% with 3 lines in your changes missing coverage. Please review.

Project coverage is 92.3%. Comparing base (47730e7) to head (7d61947).

Files with missing lines	Patch %	Lines
src/dd/FunctionalityConstruction.cpp	82.3%	3 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main    #831   +/-   ##
=====================================
  Coverage   92.3%   92.3%           
=====================================
  Files        127     127           
  Lines      13520   13555   +35     
  Branches    2081    2086    +5     
=====================================
+ Hits       12487   12522   +35     
  Misses      1033    1033           

Flag	Coverage Δ
cpp	92.1% <95.4%> (+<0.1%)	⬆️
python	99.7% <ø> (ø)

Files with missing lines	Coverage Δ
include/mqt-core/dd/CachedEdge.hpp	84.2% <ø> (ø)
include/mqt-core/dd/Complex.hpp	100.0% <ø> (ø)
include/mqt-core/dd/ComplexValue.hpp	87.5% <ø> (ø)
include/mqt-core/dd/ComputeTable.hpp	100.0% <100.0%> (ø)
include/mqt-core/dd/Edge.hpp	94.1% <ø> (ø)
include/mqt-core/dd/Operations.hpp	75.5% <100.0%> (ø)
include/mqt-core/dd/Package.hpp	96.8% <100.0%> (ø)
include/mqt-core/dd/Simulation.hpp	100.0% <ø> (ø)
include/mqt-core/dd/UnaryComputeTable.hpp	92.0% <100.0%> (-0.6%)	⬇️
src/dd/Simulation.cpp	93.5% <100.0%> (ø)
... and 1 more