Add test or example to for vulnerability-config-based vulnerability curve uncertainty

[joemoorhouse]

We have defined a methodology and format for capturing uncertainty in vulnerability curves, as described here in https://physrisk.readthedocs.io/en/latest/user_guide/vulnerability/vulnerability_uncertainty.html

This is also implemented in the class CDFBasedVulnerabilityFunction, which takes either a full cumulative density function (CDF) or standard deviations which can be used to create a CDF under different assumptions, and which can then create a conditional probability matrix via the prob_matrix_for_indicator_bins method. Module config_based_uncertainty_test.py contains tests of this class.

However, the class is not yet connected into the ConfigBasedVulnerabilityModelAcute class (only a stub exists). The work is to finish this plumbing and illustrate how that is used.

[joemoorhouse]

FYI @jmcarmonacejas. We are indeed missing some plumbing (overlooked when contributing back the feature). I have started work on that now. We need to capture the interpretation of the data in the VulnerabilityConfigItem, for which I added a points_kind attribute and then change ConfigBasedVulnerabilityModelAcute to use CDFBasedVulnerabilityFunction.