FE: add & fix test with intersection property shadowed by base field

compiler/testData/diagnostics/tests/derivedIntersectionPropertyShadowsBaseClassField.fir.kt

@@ -0,0 +1,23 @@
+// WITH_STDLIB
+// FIR_DUMP
+// FILE: Base.java
+
+public class Base {
+    public String x = "";
+}
+
+// FILE: test.kt
+
+interface Proxy {
+    val x: String
+}
+
+open class Intermediate : Base() {
+    val x get() = " "
+}
+
+class Derived : Proxy, Intermediate() {
+    fun test() {
+        x
+    }
+}