[IR, Tests] Add context receivers count to IR dump

compiler/testData/ir/irText/declarations/contextReceivers/plusMatrix.ir.txt

@@ -38,6 +38,7 @@ FILE fqName:<root> fileName:/plusMatrix.kt
         public open fun toString (): kotlin.String declared in kotlin.Any
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any
   FUN name:plus visibility:public modality:FINAL <> ($receiver:<root>.Matrix, <this>:<root>.NumberOperations, other:<root>.Matrix) returnType:<root>.Matrix
+    contextReceiverParametersCount: 1
     $receiver: VALUE_PARAMETER name:<this> type:<root>.Matrix
     VALUE_PARAMETER name:<this> index:0 type:<root>.NumberOperations
     VALUE_PARAMETER name:other index:1 type:<root>.Matrix