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 |
```

1 files changed, 5 insertions, 5 deletions

diff --git a/Emby.Server.Implementations/Channels/ChannelManager.cs b/Emby.Server.Implementations/Channels/ChannelManager.cs
index 2d5b19fa6..8c5fa09f6 100644
--- a/Emby.Server.Implementations/Channels/ChannelManager.cs
+++ b/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>();
             }
         }