Allow `GetFileSize` to follow symlinks

(cherry picked from commit ca0bb14027f3409014e7cf9ffa8e04e577001d77)

src/NzbDrone.Common/Disk/DiskProviderBase.cs

@@ -189,6 +189,18 @@ namespace NzbDrone.Common.Disk
             }
 
             var fi = new FileInfo(path);
+
+            // If the file is a symlink, resolve the target path and get the size of the target file.
+            if (fi.Attributes.HasFlag(FileAttributes.ReparsePoint))
+            {
+                var targetPath = fi.ResolveLinkTarget(true)?.FullName;
+
+                if (targetPath != null)
+                {
+                    fi = new FileInfo(targetPath);
+                }
+            }
+
             return fi.Length;
         }