New: Add result to commands to report commands that did not complete successfully

(cherry picked from commit 103ce3def4636ef891e72bd687ef8f46b5125233)

src/Readarr.Api.V1/Commands/CommandResource.cs

@@ -17,6 +17,7 @@ namespace Readarr.Api.V1.Commands
         public Command Body { get; set; }
         public CommandPriority Priority { get; set; }
         public CommandStatus Status { get; set; }
+        public CommandResult Result { get; set; }
         public DateTime Queued { get; set; }
         public DateTime? Started { get; set; }
         public DateTime? Ended { get; set; }
@@ -102,6 +103,7 @@ namespace Readarr.Api.V1.Commands
                 Body = model.Body,
                 Priority = model.Priority,
                 Status = model.Status,
+                Result = model.Result,
                 Queued = model.QueuedAt,
                 Started = model.StartedAt,
                 Ended = model.EndedAt,