Add GraphQL mutation to delete release asset link

What does this MR do?

Adds a GraphQL mutation - releaseAssetLinkDelete - to delete a release asset link.

This new mutation is equivalent to the existing REST API update endpoint:

DELETE /projects/:id/releases/:tag_name/assets/links/:link_id

This MR is very similar to these MRs:

• !54605 (merged), where a creation mutation was added, and
• !56265 (merged), where an update mutation was added

Example query/response

When a link is successfully deleted

Query:

mutation {
  releaseAssetLinkDelete(input: {id: "gid://gitlab/Releases::Link/187"}) {
    link {
      id
      name
      url
      directAssetUrl
      linkType
      external
    }
    errors
  }
}

Response:

{
  "data": {
    "releaseAssetLinkDelete": {
      "link": {
        "id": "gid://gitlab/Releases::Link/187",
        "name": "A link",
        "url": "https://example.com/link",
        "directAssetUrl": "https://example.com/link",
        "linkType": "OTHER",
        "external": true
      },
      "errors": []
    }
  }
}

When the provided link doesn't exist

In this example, there's no link with an ID of 999999.

Query:

mutation {
  releaseAssetLinkDelete(input: {id: "gid://gitlab/Releases::Link/999999"}) {
    link {
      id
      name
      url
      directAssetUrl
      linkType
      external
    }
    errors
  }
}

Response:

{
  "data": {
    "releaseAssetLinkDelete": null
  },
  "errors": [
    {
      "message": "The resource that you are attempting to access does not exist or you don't have permission to perform this action",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "releaseAssetLinkDelete"
      ]
    }
  ]
}

When the user doesn't have permission to delete

In this example, the user has Developer permissions to the project.

Query:

mutation {
  releaseAssetLinkDelete(input: {id: "gid://gitlab/Releases::Link/188"}) {
    link {
      id
      name
      url
      directAssetUrl
      linkType
      external
    }
    errors
  }
}

Response:

{
  "data": {
    "releaseAssetLinkDelete": null
  },
  "errors": [
    {
      "message": "The resource that you are attempting to access does not exist or you don't have permission to perform this action",
      "locations": [
        {
          "line": 2,
          "column": 3
        }
      ],
      "path": [
        "releaseAssetLinkDelete"
      ]
    }
  ]
}

Permissions

Permissions for this endpoint mirror the existing REST API update endpoint.