Properly verify args in string concatenation expression for interpreter

If string concatenation contains object value, then this argument
will not have explicit toString call. We must find and check toString
method manually.

#KT-54615

compiler/testData/codegen/box/evaluate/stringConcatenationWithObject.kt

@@ -0,0 +1,15 @@
+// TARGET_BACKEND: JVM_IR
+
+object K : Code("K")
+
+open class Code(val x: String) {
+    override fun toString() = "$x"
+}
+
+class O {
+    companion object: Code("O")
+}
+
+fun box(): String {
+    return "$O" + "$K" // must not be evaluated during compile time
+}