Implement project management for the instance security dashboard

What does this MR do?

This MR implements the backend for project management for the instance level security dashboard. It does this primarily by reusing the logic for project management on the operations dashboard.

• Refactors UsersOpsDashboardProjects::CreateService into Dashboard::Projects::CreateService, which can add projects for both the operations and security dashboards
• Refactors Dashboard::Operations::ProjectsService into Dashboard::Projects::ListService
• Adds a serializer and entity for the security dashboard's projects
• Cleans up some unnecessary argument passing in the operation dashboard controller

Issue: #33896 (closed) Epic: #6953 (closed)

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team