[Suggestion] Replace 'throw new ArgumentNullException' with 'ArgumentNullException.ThrowIfNull' where applicable

This is a very minor thing but it is slightly less error-prone and is a little more compact.
```cs
//Before
if (foo == null)
throw new ArgumentNullException(nameof (foo));

//After
ArgumentNullException.ThrowIfNull(foo);
```
Here's an example of where this change would apply
https://github.com/FlaxEngine/FlaxEngine/blob/dcadb11a2045416675c2c85c0fc3d7720d28a123/Source/Engine/Utilities/Extensions.cs#L148