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, 2 insertions, 4 deletions

diff --git a/Emby.Server.Implementations/Plugins/PluginManager.cs b/Emby.Server.Implementations/Plugins/PluginManager.cs
index 1ab01252d..e7fcc1f58 100644
--- a/Emby.Server.Implementations/Plugins/PluginManager.cs
+++ b/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);
                 }