Don't let permission denied kill library scans

I have a single `./Movies` directory that contains symlinks to many
other directories, some of which are in shared paths. Other daemons
sometimes overwrite permissions on these paths and prevent Jellyfin from
being able to scan. Because this exception is unhandled within a LINQ
statement it can randomly kill the metadata refresh for my entire Movies
library.

Running with this patch has allowed me to at least add + scan for
movies in directories that Jellyfin can currently access and gives me
some notification of the symlinks failing due to permissions errors.

(cherry picked from commit 193cc8690a60bc2a432df14d256f00371e055c90)

Emby.Server.Implementations/IO/ManagedFileSystem.cs

@@ -262,6 +262,10 @@ namespace Emby.Server.Implementations.IO
                             _logger.LogError(ex, "Reading the file size of the symlink at {Path} failed. Marking the file as not existing.", fileInfo.FullName);
                             result.Exists = false;
                         }
+                        catch (UnauthorizedAccessException ex)
+                        {
+                            _logger.LogError(ex, "Reading the file at {Path} failed due to a permissions exception.", fileInfo.FullName);
+                        }
                     }
                 }