FIR2IR: add extension receiver parameters to functions

compiler/testData/ir/irText/expressions/thisOfGenericOuterClass.fir.txt

@@ -62,7 +62,8 @@ FILE fqName:<root> fileName:/thisOfGenericOuterClass.kt
       overridden:
         public open fun toString (): kotlin.String declared in kotlin.Any
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any 
-  FUN name:test visibility:public modality:FINAL <> () returnType:<root>.Outer.Inner<kotlin.Int> 
+  FUN name:test visibility:public modality:FINAL <> ($receiver:<root>.Outer<kotlin.Int>) returnType:<root>.Outer.Inner<kotlin.Int>
+    $receiver: VALUE_PARAMETER name:<this> type:<root>.Outer<kotlin.Int>
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='public final fun test (): <root>.Outer.Inner<kotlin.Int> declared in <root>'
         BLOCK type=<root>.test.<no name provided> origin=OBJECT_LITERAL