Add missing decompiler-settings resource strings

CovariantReturns (C# 9), InlineArrays (C# 12) and ExtensionMembers (C# 14)
are exposed in the decompiler options UI via [Description("DecompilerSettings.X")]
but had no entry in Resources.resx, so each showed its raw resource key instead
of a label. Add the three strings. AggressiveScalarReplacementOfAggregates is
left out deliberately: it is [Browsable(false)] outside DEBUG, so users never
see it.

Assisted-by: Claude:claude-opus-4-8:Claude Code

ILSpy/Properties/Resources.resx

@@ -300,6 +300,9 @@ Are you sure you want to continue?</value>
   <data name="DecompilerSettings.CheckedOperators" xml:space="preserve">
     <value>User-defined checked operators</value>
   </data>
+  <data name="DecompilerSettings.CovariantReturns" xml:space="preserve">
+    <value>Covariant return types</value>
+  </data>
   <data name="DecompilerSettings.DecompileAnonymousMethodsLambdas" xml:space="preserve">
     <value>Decompile anonymous methods/lambdas</value>
   </data>
@@ -369,6 +372,9 @@ Are you sure you want to continue?</value>
   <data name="DecompilerSettings.ExpandParamsArguments" xml:space="preserve">
     <value>Expand params arguments by removing explicit array creation</value>
   </data>
+  <data name="DecompilerSettings.ExtensionMembers" xml:space="preserve">
+    <value>Decompile extension members</value>
+  </data>
   <data name="DecompilerSettings.FSpecificOptions" xml:space="preserve">
     <value>F#-specific options</value>
   </data>
@@ -393,6 +399,9 @@ Are you sure you want to continue?</value>
   <data name="DecompilerSettings.InitAccessors" xml:space="preserve">
     <value>Allow init; accessors</value>
   </data>
+  <data name="DecompilerSettings.InlineArrays" xml:space="preserve">
+    <value>Inline arrays</value>
+  </data>
   <data name="DecompilerSettings.InsertUsingDeclarations" xml:space="preserve">
     <value>Insert using declarations</value>
   </data>