Establish pattern for organizing Secure backend (Rails) code

Summary

As the Secure and Defend specific code within the monolith expands, it may be useful to establish patterns on how to namespace and organize that code.

Context on the creation of this issue

The following discussion from !32577 (merged) should be addressed:

• @avielle started a discussion: (+6 comments)

  We have the security directory in ee/app/models. Would it make sense to nest this model in there?

The code

Security namespace

The Security::Scan model lives in the Security namespace

1. Should other models exist in this namespace?
2. Is "security" a good name? Is it too broad?

Dashboard models

1. UsersSecurityDashboardProject could become Security::UsersDashboardProject
2. InstanceSecurityDashboard could be come Security::InstanceDashboard

Proposal Reviewed

• @d0c-s4vage
• @cam_swords
• @theoretick
• @fcatteau
• @markrian

Vulnerabilities namespace

This namespace is fairly established with 7 models in it.