JsonSerializer deserialize from bytes where possible

This is faster and uses way less memory
```
BenchmarkDotNet=v0.12.1, OS=fedora 32
Intel Core i7-6700HQ CPU 2.60GHz (Skylake), 1 CPU, 8 logical and 4 physical cores
.NET Core SDK=5.0.100
  [Host]     : .NET Core 5.0.0 (CoreCLR 5.0.20.51904, CoreFX 5.0.20.51904), X64 RyuJIT
  DefaultJob : .NET Core 5.0.0 (CoreCLR 5.0.20.51904, CoreFX 5.0.20.51904), X64 RyuJIT

| Method |     Mean |   Error |  StdDev |   Gen 0 | Gen 1 | Gen 2 | Allocated |
|------- |---------:|--------:|--------:|--------:|------:|------:|----------:|
|  Bytes | 158.4 us | 2.56 us | 2.14 us | 16.8457 |     - |     - |  52.08 KB |
| String | 172.8 us | 0.78 us | 0.70 us | 41.5039 |     - |     - | 127.82 KB |
| Custom | 155.5 us | 2.95 us | 2.76 us | 10.0098 |     - |     - |  31.27 KB |
```

Emby.Server.Implementations/Channels/ChannelManager.cs

@@ -336,19 +336,19 @@ namespace Emby.Server.Implementations.Channels
             return GetChannel(GetInternalChannelId(channel.Name)) ?? GetChannel(channel, CancellationToken.None).Result;
         }
 
-        private List<MediaSourceInfo> GetSavedMediaSources(BaseItem item)
+        private MediaSourceInfo[] GetSavedMediaSources(BaseItem item)
         {
             var path = Path.Combine(item.GetInternalMetadataPath(), "channelmediasourceinfos.json");
 
             try
             {
-                var jsonString = File.ReadAllText(path, Encoding.UTF8);
-                return JsonSerializer.Deserialize<List<MediaSourceInfo>>(jsonString, _jsonOptions)
-                    ?? new List<MediaSourceInfo>();
+                var bytes = File.ReadAllBytes(path);
+                return JsonSerializer.Deserialize<MediaSourceInfo[]>(bytes, _jsonOptions)
+                    ?? Array.Empty<MediaSourceInfo>();
             }
             catch
             {
-                return new List<MediaSourceInfo>();
+                return Array.Empty<MediaSourceInfo>();
             }
         }
 

Emby.Server.Implementations/LiveTv/EmbyTV/ItemDataProvider.cs

@@ -47,11 +47,11 @@ namespace Emby.Server.Implementations.LiveTv.EmbyTV
 
                 try
                 {
-                    var jsonString = File.ReadAllText(_dataPath, Encoding.UTF8);
-                    _items = JsonSerializer.Deserialize<T[]>(jsonString, _jsonOptions);
+                    var bytes = File.ReadAllBytes(_dataPath);
+                    _items = JsonSerializer.Deserialize<T[]>(bytes, _jsonOptions);
                     return;
                 }
-                catch (Exception ex)
+                catch (JsonException ex)
                 {
                     Logger.LogError(ex, "Error deserializing {Path}", _dataPath);
                 }

Emby.Server.Implementations/Plugins/PluginManager.cs

@@ -514,12 +514,10 @@ namespace Emby.Server.Implementations.Plugins
             {
                 try
                 {
-                    var data = File.ReadAllText(metafile, Encoding.UTF8);
+                    var data = File.ReadAllBytes(metafile);
                     manifest = JsonSerializer.Deserialize<PluginManifest>(data, _jsonOptions);
                 }
-#pragma warning disable CA1031 // Do not catch general exception types
-                catch (Exception ex)
-#pragma warning restore CA1031 // Do not catch general exception types
+                catch (JsonException ex)
                 {
                     _logger.LogError(ex, "Error deserializing {Path}.", dir);
                 }

Emby.Server.Implementations/ScheduledTasks/ScheduledTaskWorker.cs

@@ -143,21 +143,21 @@ namespace Emby.Server.Implementations.ScheduledTasks
                     {
                         if (File.Exists(path))
                         {
-                            try
+                            var bytes = File.ReadAllBytes(path);
+                            if (bytes.Length > 0)
                             {
-                                var jsonString = File.ReadAllText(path, Encoding.UTF8);
-                                if (!string.IsNullOrWhiteSpace(jsonString))
+                                try
                                 {
-                                    _lastExecutionResult = JsonSerializer.Deserialize<TaskResult>(jsonString, _jsonOptions);
+                                    _lastExecutionResult = JsonSerializer.Deserialize<TaskResult>(bytes, _jsonOptions);
                                 }
-                                else
+                                catch (JsonException ex)
                                 {
-                                    _logger.LogDebug("Scheduled Task history file {Path} is empty. Skipping deserialization.", path);
+                                    _logger.LogError(ex, "Error deserializing {File}", path);
                                 }
                             }
-                            catch (Exception ex)
+                            else
                             {
-                                _logger.LogError(ex, "Error deserializing {File}", path);
+                                _logger.LogDebug("Scheduled Task history file {Path} is empty. Skipping deserialization.", path);
                             }
                         }
 
@@ -541,8 +541,8 @@ namespace Emby.Server.Implementations.ScheduledTasks
             TaskTriggerInfo[] list = null;
             if (File.Exists(path))
             {
-                var jsonString = File.ReadAllText(path, Encoding.UTF8);
-                list = JsonSerializer.Deserialize<TaskTriggerInfo[]>(jsonString, _jsonOptions);
+                var bytes = File.ReadAllBytes(path);
+                list = JsonSerializer.Deserialize<TaskTriggerInfo[]>(bytes, _jsonOptions);
             }
 
             // Return defaults if file doesn't exist.

Jellyfin.Server/Migrations/Routines/MigrateDisplayPreferencesDb.cs

@@ -90,7 +90,7 @@ namespace Jellyfin.Server.Migrations.Routines
                 var results = connection.Query("SELECT * FROM userdisplaypreferences");
                 foreach (var result in results)
                 {
-                    var dto = JsonSerializer.Deserialize<DisplayPreferencesDto>(result[3].ToString(), _jsonOptions);
+                    var dto = JsonSerializer.Deserialize<DisplayPreferencesDto>(result[3].ToBlob(), _jsonOptions);
                     if (dto == null)
                     {
                         continue;