FIR2IR: declare receivers for all accessors of extension properties

Before this commit, extension receivers were declared only for
properties with container source, which is strange & inconsistent.
Now we declare accessor extension receiver iff corresponding property
has extension receiver.

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

@@ -243,5 +243,6 @@ FILE fqName:<root> fileName:/complexAugmentedAssignment.kt
     BLOCK_BODY
       CALL 'public final fun plusAssign (b: <root>.B): kotlin.Unit [operator] declared in <root>.Host' type=kotlin.Unit origin=null
         $this: GET_VAR '<this>: <root>.Host declared in <root>.test3' type=<root>.Host origin=null
+        $receiver: GET_VAR 'v: <root>.B declared in <root>.test3' type=<root>.B origin=null
         b: CONSTRUCTOR_CALL 'public constructor <init> (s: kotlin.Int) [primary] declared in <root>.B' type=<root>.B origin=null
           s: CONST Int type=kotlin.Int value=1000