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

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

@@ -19,6 +19,7 @@ FILE fqName:<root> fileName:/overloadPriority.kt
         public open fun toString (): kotlin.String declared in kotlin.Any
       $this: VALUE_PARAMETER name:<this> type:kotlin.Any
   FUN name:f visibility:public modality:FINAL <> (<this>:<root>.Context) returnType:kotlin.String
+    contextReceiverParametersCount: 1
     VALUE_PARAMETER name:<this> index:0 type:<root>.Context
     BLOCK_BODY
       RETURN type=kotlin.Nothing from='public final fun f (<this>: <root>.Context): kotlin.String declared in <root>'