Number of affected risks output

[benhayes21]

Issue Description

There is a requirement to create a measure of the number of affected risks in an analysis.

Proposal, to be discussed, is that we create a new output report which counts the number of summary_ids with a sidx -1value > 0 at event_id level.

supported by new python module summurypy in: https://github.com/OasisLMF/OasisLMF/pull/1482

[johcarter]

We already have some ORD fields to report this information, rather than create a new report

[benhayes21]

To discuss whether we can link through to gul summary map to get number of locations

[benhayes21]

can we recycle -4 sidx for number of locations?

[hchagani-oasislmf]

can we recycle -4 sidx for number of locations?

I don't see why not. The downstream components either carry this sidx forward or discard it. This behaviour can be changed.