Revised POMDP belief exploration

[AlexBork]

This PR contains the revised POMDP belief exploration implementation.
The revised implementation is more modular, making it easier to add extensions.
In addition, it is more performant than the old one.

This PR also adds the functionality to analyse reward-bounded reachability properties on POMDP, as described in https://proceedings.mlr.press/v286/bork25a.html

In the long-term, the revised implementation is supposed to fully replace the current one.
In partiucular, the plan is to not immediately port over all functionality, but to check which features we want to keep.
Thus, the current implementation is deprecated, but not removed.

Changes outside of Storm-POMDP are part of separate PR #1028

[sjunges]

What besides SAYNT may depend on the old one? I understand the desire to treat carefully, but I also think it may simplify the merging process significantly if we do hard cut. People that want the old version will need to work with 1.14 and as long as it is clear what features we are loosing, that all seems fine to me.

[AlexBork]

I can't think of anything that depends on the old one besides SAYNT. Featurewise, I think the only significant omission currently is the automated refinement loop for the approximations. I think that needs some conceptual reworking before implementation, so I have omitted it for now.

All in all, I would be fine with completely removing the old implementation. As we are reworking SAYNT, there should be no reason for keeping it.

[sjunges]

Would it make sense to split this PR into one that touches storm and one that only touches storm-pomdp? Also, within storm-pomdp, I was wondering whether some parts of the CLI should actually be moved into their own header/cpp (pomdp-handling.h) or so such that it is a bit clearer where it is just cli handling and where it is configuring the algorithm?

[AlexBork]

I'll split the PR. That definitely makes things more manageable.
The CLI handling also sounds reasonable. I'll look into it if I find some time.