QCEC 2.0 Release Candidate 6

This release mostly concerns the internal library and contains almost no user facing changes (besides some bugfixes 🐛).

It significantly improves the code quality and its assurance. To this end,

• the project now follows and enforces (most of) LLVM's code format style and coding guidelines for the C++ part, including consistent naming schemes and source code width limits
• several improvements reported by the SonarLint tool and various clang-tidy checks have been incorporated
• similar to the C++ workflow which has been quite well monitored, the Python side of the project now adopts the best practices from https://scikit-hep.org/developer in order to maintain a consistent and high quality

All these changes ensure that future contributions to QCEC can follow predefined guidelines and rules, whether it's for developing the core C++ library or the Python package.

What's Changed

• 🚨 Incorporate SonarLint Suggestions by @burgholzer in #88
• 👷🚨 Add new workflow run for checking clang-tidy and clang-format by @burgholzer in #89
• 🚸 Improve Python Compatibility of Documentation Building by @burgholzer in #90
• 📝 Small documentation update by @burgholzer in #91
• ⚡🔧 Faster CI by @burgholzer in #94
• 🎨🔧 Adopt (most of) LLVM's Code Format Style by @burgholzer in #97
• ⚡ Avoid vtable Copy by @burgholzer in #98
• 🎨🔧 Further clang-tidy Setup by @burgholzer in #99
• 🐍🔧 Python Development Setup by @burgholzer in #100
• 🐛 Fix Potential Endless Loop by @burgholzer in #102

Full Changelog: v2.0.0-rc5...v2.0.0-rc6