C#: Fixup of the PrintAst test.

Author: michaelnebel

csharp/ql/test/library-tests/extension/PrintAst.expected

@@ -12,7 +12,7 @@ extensions.cs:
 #    6|             -1: [TypeMention] string
 #    8|         4: [GTExpr] ... > ...
 #    8|           0: [PropertyCall] access to property Length
-#    8|             -1: [SyntheticParameterAccess] access to synthetic parameter s
+#    8|             -1: [SyntheticExtensionParameter] access to extension synthetic parameter s
 #    8|           1: [IntLiteral] 0
 #    9|     5: [Property] Prop2
 #    9|       -1: [TypeMention] bool
@@ -41,7 +41,7 @@ extensions.cs:
 #    6|         0: [Parameter] s
 #    6|           -1: [TypeMention] string
 #   11|       4: [IsExpr] ... is ...
-#   11|         0: [SyntheticParameterAccess] access to synthetic parameter s
+#   11|         0: [SyntheticExtensionParameter] access to extension synthetic parameter s
 #   11|         1: [NotPatternExpr] not ...
 #   11|           0: [ConstantPatternExpr,NullLiteral] null
 #   12|     8: [ExtensionMethod] M2
@@ -54,7 +54,7 @@ extensions.cs:
 #   12|       4: [BlockStmt] {...}
 #   12|         0: [ReturnStmt] return ...;
 #   12|           0: [AddExpr] ... + ...
-#   12|             0: [SyntheticParameterAccess] access to synthetic parameter s
+#   12|             0: [SyntheticExtensionParameter] access to extension synthetic parameter s
 #   12|             1: [ParameterAccess] access to parameter other
 #   13|     9: [ExtensionMethod] StaticM1
 #   13|       -1: [TypeMention] int
@@ -126,7 +126,7 @@ extensions.cs:
 #   26|           0: [Parameter] t
 #   26|             -1: [TypeMention] T
 #   28|         4: [IsExpr] ... is ...
-#   28|           0: [SyntheticParameterAccess] access to synthetic parameter t
+#   28|           0: [SyntheticExtensionParameter] access to extension synthetic parameter t
 #   28|           1: [NotPatternExpr] not ...
 #   28|             0: [ConstantPatternExpr,NullLiteral] null
 #   29|     5: [Property] GenericProp2
@@ -150,7 +150,7 @@ extensions.cs:
 #   26|         0: [Parameter] t
 #   26|           -1: [TypeMention] T
 #   30|       4: [IsExpr] ... is ...
-#   30|         0: [SyntheticParameterAccess] access to synthetic parameter t
+#   30|         0: [SyntheticExtensionParameter] access to extension synthetic parameter t
 #   30|         1: [NotPatternExpr] not ...
 #   30|           0: [ConstantPatternExpr,NullLiteral] null
 #   31|     7: [ExtensionMethod] GenericM2`1