⚡ Skip symmetry computation and 🔥 remove transpose method

[burgholzer]

Description

This PR removes the computation of the isSymmetric property in matrix DDs.
The corresponding check was conducted on every node creation in makeDDNode and the resulting property was only used as a shortcut in the transpose method.
However, the transpose method is not used anywhere in our codebase.
As a consequence, this PR also removes the transpose method to reduce the amount of code bloat in our code base.

Overall, this should yield a small net performance gain for every operation involving matrices.

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

Merging #442 (5925309) into main (9ad0c72) will decrease coverage by 0.1%.
The diff coverage is 100.0%.

Additional details and impacted files

@@           Coverage Diff           @@
##            main    #442     +/-   ##
=======================================
- Coverage   90.1%   90.0%   -0.1%     
=======================================
  Files        108     108             
  Lines      11889   11853     -36     
  Branches    2089    2082      -7     
=======================================
- Hits       10712   10676     -36     
  Misses      1177    1177             

Flag	Coverage Δ
cpp	89.8% <100.0%> (-0.1%)	⬇️
python	100.0% <ø> (ø)

Files	Coverage Δ
include/dd/Node.hpp	100.0% <ø> (ø)
include/dd/Package.hpp	94.3% <100.0%> (-0.1%)	⬇️
include/dd/statistics/PackageStatistics.hpp	100.0% <ø> (ø)

[github-actions]

Cpp-Linter Report ✔️

No problems need attention.

Have any feedback or feature suggestions? Share it here.