PWL Impact Calculation Metric

[gkahiu]

This PR incorporates a metric for calculating the PWL impact of an activity. It provides an implementation for #576.

[github-actions]

Plugin zip package for the changes in this PR has been successfully built!.

Download the plugin zip file here https://github.com/ConservationInternational/cplus-plugin/suites/31980588269/artifacts/2311240915

[amyburness]

@gkahiu Test there is an error as follows:
library looks good

able to add espression

generation fails

[gkahiu]

@amyburness, most likely the area is zero for one or more activities. To confirm, could you:

1. Remove the 'pwl' column and try re-running the scenario;
2. After running the scenario, check if there are output activities under 'Weighted Activity Maps' legend group:

[amyburness]

@gkahiu
there is an output and they activities appear in the output