DRY up extracted report type modules in Security Reports store

As part of moving reports logic for security reports to the backend, the security reports Vuex store is being split up into report-category-specific submodules. For instance, see the MR that created the SAST module.

Within that MR, it was noted that the (eventually) extracted modules would be very similar, which could lead to maintenance problems.

This issue is the place to discuss how to DRY of these modules, and track the progress of that effort.