Project Setting: Add toggle to remove Security & Compliance left nav item (BE)

Why are we doing this work

In project settings, there are a number of left sidebar menu items that can be toggled off such as the repository, issues, and snippets; however, there are a number of items that cannot be toggled off which leads to a poor user experience if the project isn't ever going to utilize those features.

We should allow users to toggle off the Security & Compliance left nav item in Project Settings => General => Visibility, Project Features, and Permissions.

This issue represents the backend work required to deliver this feature. The frontend work is tracked in #224697 (closed).

Relevant links

Non-functional requirements

• Documentation:
• Feature flag:
• Performance:
• Testing:

Implementation plan

• Add a new column into project_features table
  • "security_dashboard_access_level integer DEFAULT 20 NOT NULL"
  • Add the model layer presence validation for the new column
• Update project_permissions_settings helper method to serialize the recently introduced column value
• Update project_feature_attributes method in projects controller to permit security_dashboard_access_level
• Update the EE::ProjectPolicy to adhere the selected permission level
• Update the InstanceSecurityDashboard#authorized_access_levels method to adhare the selected permission level