✨ Scalable Clifford (sub-)circuit optimizer

What's the problem this feature will solve?

Currently, a depth-optimal Clifford synthesis is implemented. Usually, depth-optimal approaches scale poorly and are thus limited by the number of qubits.

A first heuristic is already implemented. However this implementation is not suited to optimize Clifford sub-circuits in a non-Clifford circuit (Issue: https://github.com/cda-tum/mqt-qmap/issues/365).

Describe the solution you'd like

To tackle the scaling problem, we can make use of scalable heuristics, such as peephole optimization.

We can do this by identifying blocks of Clifford gates and optimizing each block within a non-Clifford Circuit.
While doing this, we can implement different strategies for performing the (peephole) optimization. Such as horizontal circuit splitting (Issue: https://github.com/cda-tum/mqt-qmap/issues/305).

Start by examining the existing depth-optimal Clifford synthesis and the first heuristic mentioned in the issue. Review Issues #365 and #305 for the non-Clifford sub-circuit and horizontal circuit-splitting context. Done means identifying Clifford blocks within non-Clifford circuits and supporting scalable peephole optimization strategies for those blocks.