C#: add debug switch to IRConfiguration

Author: rdmarsh2

csharp/ql/src/semmle/code/csharp/ir/IRConfiguration.qll

@@ -5,6 +5,7 @@
 import csharp
 
 private newtype TIRConfiguration = MkIRConfiguration()
+private import semmle.code.csharp.ir.internal.IRCSharpLanguage as Language
 
 /**
  * The query can extend this class to control which functions have IR generated for them.
@@ -16,4 +17,6 @@ class IRConfiguration extends TIRConfiguration {
    * Holds if IR should be created for callable `callable`. By default, holds for all callables.
    */
   predicate shouldCreateIRForFunction(Callable callable) { any() }
+
+  predicate shouldEvaluateDebugStringsForFunction(Language::Function func) { any() }
 }