New API endpoint GET /projects/:id/services

What does this MR do?

Closes #18659 (closed) by adding the requested endpoint.

The proposed solution was to add an endpoint that returns just the active services and another one to return all, or to add a filter parameter. As a first iteration I made an endpoint that just returns all services. Filtering would be up to the frontend but we can add a filter parameter in the next iteration.

The returned fields will be id, title, created_at, updated_at and active. This should be enough to display the status and sort by title, created or updated_at. For more details GET project/:id/services/:name can be used

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
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• 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

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• [-] 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
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