Get Project's environment names via GraphQL

What does this MR do?

As part of #36619 (closed), we want to use the GraphQL API to fetch environment data. As an MVC, this returns the environments for a given project with fields id and name, and allows for searching by name (which is the minimum needed to be helpful for some upcoming monitor features, as discussed here: #34021 (comment 253613599)). The next iterations can include computed properties (for example, logs_path and metrics_path).

The user can query for all environments for a given project:

{
  project(fullPath: "gitlab-org/gitlab-test") {
    environments {
      nodes {
        name
        id
      }
    }
  }
}

And also search for environments by name:

  project(fullPath: "root/kube-test") {
    environments(search: "test") {
      nodes {
        name
        id
      }
    }
  }
}

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• [x 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