Use ArgumentNullException.ThrowIfNull helper method

Did a simple search/replace on the whole repo (except the RSSDP project)
This reduces LOC and should improve performance (methods containing a throw statement don't get inlined)

```
if \((\w+) == null\)
\s+\{
\s+throw new ArgumentNullException\((.*)\);
\s+\}
```

```
ArgumentNullException.ThrowIfNull($1);
```

1 files changed, 2 insertions, 8 deletions

diff --git a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
index 42c5517f9..d0362b128 100644
--- a/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
+++ b/MediaBrowser.Controller/MediaEncoding/EncodingHelper.cs
@@ -5105,15 +5105,9 @@ namespace MediaBrowser.Controller.MediaEncoding
             MediaSourceInfo mediaSource,
             string requestedUrl)
         {
-            if (state == null)
-            {
-                throw new ArgumentNullException(nameof(state));
-            }
+            ArgumentNullException.ThrowIfNull(state);
 
-            if (mediaSource == null)
-            {
-                throw new ArgumentNullException(nameof(mediaSource));
-            }
+            ArgumentNullException.ThrowIfNull(mediaSource);
 
             var path = mediaSource.Path;
             var protocol = mediaSource.Protocol;