V14: OpenAPI: Explicitly set ByRelationTypeKey endpoint name (#16729)

This is because of an `operationId` name clash with `ByKeyRelationTypeController.ByKey`,
ref: https://github.com/umbraco/Umbraco-CMS/blob/release-14.0.0/src/Umbraco.Cms.Api.Management/Controllers/RelationType/ByKeyRelationTypeController.cs#L27

This change attempts to ensure a unique `operationId` in the OpenAPI/Swagger JSON.

src/Umbraco.Cms.Api.Management/Controllers/Relation/ByRelationTypeKeyRelationController.cs

@@ -1,4 +1,4 @@
-using Asp.Versioning;
+using Asp.Versioning;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc;
 using Umbraco.Cms.Api.Common.ViewModels.Pagination;
@@ -29,7 +29,7 @@ public ByRelationTypeKeyRelationController(IRelationService relationService, IRe
     /// <remarks>
     /// Use case: On a relation type page you can see all created relations of this type.
     /// </remarks>
-    [HttpGet("type/{id:guid}")]
+    [HttpGet("type/{id:guid}", Name = "GetRelationByRelationTypeId")]
     [MapToApiVersion("1.0")]
     [ProducesResponseType(typeof(PagedViewModel<RelationResponseModel>), StatusCodes.Status200OK)]
     [ProducesResponseType(typeof(PagedViewModel<ProblemDetails>), StatusCodes.Status404NotFound)]