FIR: Ensure that the array set argument (on RHS of =) is always mapped

to the last parameter of the set operator function, even if there are
missing or too many index arguments.

compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetNotEnoughArgs.kt

@@ -0,0 +1,10 @@
+// FIR_IDENTICAL
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    operator fun set(x: String, y: Boolean, value: Int) {}
+
+    fun d(x: Int) {
+        <!NO_VALUE_FOR_PARAMETER("y")!>this[""]<!> = 1
+    }
+}

compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetNotEnoughArgs.txt

@@ -0,0 +1,10 @@
+package
+
+public final class A {
+    public constructor A()
+    public final fun d(/*0*/ x: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun set(/*0*/ x: kotlin.String, /*1*/ y: kotlin.Boolean, /*2*/ value: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetTooManyArgs.fir.kt

@@ -0,0 +1,10 @@
+// !DIAGNOSTICS: -UNUSED_PARAMETER
+
+class A {
+    operator fun get(x: Int) {}
+    operator fun set(x: String, value: Int) {}
+
+    fun d(x: Int) {
+        this["", <!TOO_MANY_ARGUMENTS!>1<!>] = 1
+    }
+}

compiler/testData/diagnostics/tests/checkArguments/arrayAccessSetTooManyArgs.kt

@@ -1,4 +1,3 @@
-// FIR_IDENTICAL
 // !DIAGNOSTICS: -UNUSED_PARAMETER
 
 class A {