Evidence sensitivity analysis

Epic: Evidence sensitivity analysis

_Overview_
Implement evidence sensitivity analysis (what-if scenarios)
This is a tool helping the appraisal and the understanding of the evaluation of the ID. It is equivalent to follow branches in the DT, but from the more compact ID representation.

_Problem Statement_
Today, only the DT can be used to interpret what-if scenarios. This goes with the general pros and cons of DTs.
Having an equivalent tool on the IDs will enable to use the advantages of an ID for adding this analysis step.

In particular, due to the exponential growth of DTs, it may be difficult to compare branches, or group of branches. In a ID this is simplified.

_Value / Impact_
Better understanding of the ID evaluation.

_Proposed Solution (What)_
We want:
1. Update the front-end so options to decisions and outcomes to uncertainties can be selected (one state per node)
2. Solve the ID with these forced decisions and hard evidences (pyagrum has these functionality)
3. Compare to the base case
1. Display MEU in both cases
2. Display course of actions in both cases
4. This may require to represent the policies (equivalent to probability tables for the decisions) on the ID
5. Optionally: we may want to compare several what-if scenarios to the base case
6. Optionally: we want to keep track of the tested what-if scenarios to emphasize an important conclusion or message to the decision maker