Add C# 11 language version.

ILSpy/Languages/CSharpLanguage.cs

@@ -115,6 +115,7 @@ namespace ICSharpCode.ILSpy
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp8_0.ToString(), "C# 8.0 / VS 2019"),
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp9_0.ToString(), "C# 9.0 / VS 2019.8"),
 						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp10_0.ToString(), "C# 10.0 / VS 2022"),
+						new LanguageVersion(Decompiler.CSharp.LanguageVersion.CSharp11_0.ToString(), "C# 11.0 / VS 2022.1"),
 					};
 				}
 				return versions;

ILSpy/Properties/Resources.Designer.cs

@@ -1118,6 +1118,15 @@ namespace ICSharpCode.ILSpy.Properties {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Use parameter null checking.
+        /// </summary>
+        public static string DecompilerSettings_ParameterNullCheck {
+            get {
+                return ResourceManager.GetString("DecompilerSettings.ParameterNullCheck", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Use pattern matching expressions.
         /// </summary>

ILSpy/Properties/Resources.resx

@@ -396,6 +396,9 @@ Are you sure you want to continue?</value>
   <data name="DecompilerSettings.Other" xml:space="preserve">
     <value>Other</value>
   </data>
+  <data name="DecompilerSettings.ParameterNullCheck" xml:space="preserve">
+    <value>Use parameter null checking</value>
+  </data>
   <data name="DecompilerSettings.PatternMatching" xml:space="preserve">
     <value>Use pattern matching expressions</value>
   </data>