New: Add backup size information

Closes #957

(cherry picked from commit 78aeda1a2cc217c367c5c3c6fd281c101b28413c)

src/NzbDrone.Core/Backup/Backup.cs

@@ -6,6 +6,7 @@ namespace NzbDrone.Core.Backup
     {
         public string Name { get; set; }
         public BackupType Type { get; set; }
+        public long Size { get; set; }
         public DateTime Time { get; set; }
     }
 }

src/NzbDrone.Core/Backup/BackupService.cs

@@ -109,6 +109,7 @@ namespace NzbDrone.Core.Backup
                     {
                         Name = Path.GetFileName(b),
                         Type = backupType,
+                        Size = _diskProvider.GetFileSize(b),
                         Time = _diskProvider.FileGetLastWrite(b)
                     }));
                 }

src/Prowlarr.Api.V1/System/Backup/BackupController.cs

@@ -42,6 +42,7 @@ namespace Prowlarr.Api.V1.System.Backup
                 Name = b.Name,
                 Path = $"/backup/{b.Type.ToString().ToLower()}/{b.Name}",
                 Type = b.Type,
+                Size = b.Size,
                 Time = b.Time
             })
                                        .OrderByDescending(b => b.Time)

src/Prowlarr.Api.V1/System/Backup/BackupResource.cs

@@ -9,6 +9,7 @@ namespace Prowlarr.Api.V1.System.Backup
         public string Name { get; set; }
         public string Path { get; set; }
         public BackupType Type { get; set; }
+        public long Size { get; set; }
         public DateTime Time { get; set; }
     }
 }