Refactoring of SCC-based Algorithms

[vhavlena]

This PR refactors SCC-based algorithms to be more generic. In particular,

• SCC-based crawler: Generic Tarjan's algorithm instantiated with event handlers. Generic enough to cover emptiness checking, useful states computation.
• Implementation of another instantiation for a checking if the NFA graph is acyclic (useful for language finiteness checking in Z3-Noodler).

[codecov[bot]]

Codecov Report

Attention: 4 lines in your changes are missing coverage. Please review.

Comparison is base (09a43aa) 71.82% compared to head (efadb56) 72.05%. Report is 12 commits behind head on devel.

Files	Patch %	Lines
src/nfa/nfa.cc	93.75%	0 Missing and 4 partials :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## devel #374 +/- ## ========================================== + Coverage 71.82% 72.05% +0.22% ========================================== Files 30 30 Lines 3642 3686 +44 Branches 834 839 +5 ========================================== + Hits 2616 2656 +40 Misses 735 735 - Partials 291 295 +4 ```

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[Adda0]

I like the new names. I think it reads better now.

[vhavlena]

@jurajsic @kilohsakul ping