[Tests] Add box tests for #KT-59904

compiler/testData/codegen/box/callableReference/adaptedReferences/unitCoercionOverloads.kt

@@ -0,0 +1,18 @@
+// IGNORE_BACKEND_K1: ANY
+
+lateinit var result: String
+
+fun foo(x: Int, y: Any): Int {
+    result = "OK"
+    return x
+}
+fun foo(x: Any, y: Int): Int {
+    result = "FAIL"
+    return y
+}
+
+fun box(): String {
+    val fooRef: (Int, Any) -> Unit = ::foo
+    fooRef(1, "")
+    return result
+}