Add support for conditional execution options for integration nodes

### 📝 Description of the feature

As a user, I want to be able to specify conditional execution options for integration nodes.

### 💡 Steps for implementing the feature

- Implement functionality on optiSLang side (AccessibleValue coverage)
- Explicit API in pyoptislang

### 🔗 Useful links and references

_No response_

Start by investigating the optiSLang-side AccessibleValue coverage and the explicit API surface in pyoptislang. Determine how integration nodes represent execution options and what the upstream support exposes. Done means users can specify conditional execution options through the pyoptislang API, with the supported behavior verified against optiSLang.

Written by the indexing model from the issue text.