Add `include_hidden`, `include_pending_delete` option to Project API

What does this MR do and why?

Contributes to https://gitlab.com/gitlab-org/gitlab/-/issues/430064

Problem

It's not possible to request projects in pending_delete or hidden state via Projects API.

Solution

Add two optional disabled by default parameters include_hidden and include_pending_delete to Projects API.

They can be set only by the admin.

Screenshots or screen recordings

Before

After

How to set up and validate locally

To verify hidden state

1. Open Rails console
2. Temporary mark last project as hidden Project.last.update(hidden: true)
3. Go to project list (http://127.0.0.1:3000/api/v4/projects)
4. The project should be missing in the list
5. Visit page http://127.0.0.1:3000/api/v4/projects?include_hidden=true as an admin
6. You should see a hidden project
7. Visit page http://127.0.0.1:3000/api/v4/projects?include_hidden=true as a regular user
8. You shouldn't see a hidden project
9. Remove hidden state from the project Project.last.update(hidden: false)

To verify pending delete state

1. Open Rails console
2. Temporary mark last project as pending delete Project.last.update(pending_delete: true)
3. Go to project list (http://127.0.0.1:3000/api/v4/projects)
4. The project should be missing in the list
5. Visit page http://127.0.0.1:3000/api/v4/projects?include_pending_delete=true as an admin
6. You should see a pending delete project
7. Visit page http://127.0.0.1:3000/api/v4/projects?include_pending_delete=true as a regular user
8. You shouldn't see a pending delete project
9. Remove pending delete state from the project Project.last.update(pending_delete: false)

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.