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);
```

2 files changed, 3 insertions, 12 deletions

diff --git a/Emby.Dlna/ContentDirectory/ContentDirectoryService.cs b/Emby.Dlna/ContentDirectory/ContentDirectoryService.cs
index 9020dea994..319a9f5500 100644
--- a/Emby.Dlna/ContentDirectory/ContentDirectoryService.cs
+++ b/Emby.Dlna/ContentDirectory/ContentDirectoryService.cs
@@ -103,10 +103,7 @@ namespace Emby.Dlna.ContentDirectory
         /// <inheritdoc />
         public Task<ControlResponse> ProcessControlRequestAsync(ControlRequest request)
         {
-            if (request == null)
-            {
-                throw new ArgumentNullException(nameof(request));
-            }
+            ArgumentNullException.ThrowIfNull(request);
 
             var profile = _dlna.GetProfile(request.Headers) ?? _dlna.GetDefaultProfile();
 
diff --git a/Emby.Dlna/ContentDirectory/ControlHandler.cs b/Emby.Dlna/ContentDirectory/ControlHandler.cs
index 57170bb316..fc69960fd6 100644
--- a/Emby.Dlna/ContentDirectory/ControlHandler.cs
+++ b/Emby.Dlna/ContentDirectory/ControlHandler.cs
@@ -114,15 +114,9 @@ namespace Emby.Dlna.ContentDirectory
         /// <inheritdoc />
         protected override void WriteResult(string methodName, IReadOnlyDictionary<string, string> methodParams, XmlWriter xmlWriter)
         {
-            if (xmlWriter == null)
-            {
-                throw new ArgumentNullException(nameof(xmlWriter));
-            }
+            ArgumentNullException.ThrowIfNull(xmlWriter);
 
-            if (methodParams == null)
-            {
-                throw new ArgumentNullException(nameof(methodParams));
-            }
+            ArgumentNullException.ThrowIfNull(methodParams);
 
             const string DeviceId = "test";