Add Remove Project custom permission

What does this MR do and why?

This MR adds 'Remove Projects' as a customizable permission, so that it can be added onto any base role.

This makes deleting projects available to all roles, as the Owner role might have too many privileges for all use cases.

Issue: #425959 (closed)

Screenshots or screen recordings

Adding the permission as group owner	Group member with custom remove_project role

How to set up and validate locally

1. Create a namespace and a project within that namespace and apply the Ultimate license to the namespace.
2. Create a new custom role that enables Delete project from Group -> Settings -> Roles and Permissions
3. Invite a user as guest to the group and assign the new custom role to the user.
4. Log in as the guest user with the custom permission and check if you can:
   • Delete the project from the UI
   • Delete the project via REST API

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.