JVM_IR: optimize out redundant delegated property receiver fields

Now this:

    class C {
        val x = something
        val y by x::property
    }

is *exactly* the same as this:

    class C {
        val x = something
        val y get() = x.property
    }

(plus a `getY$delegate` method)

compiler/testData/codegen/box/delegatedProperty/delegateToAnotherWithSideEffects.kt

@@ -0,0 +1,16 @@
+// WITH_RUNTIME
+var result = "Fail"
+
+object O {
+    val z = 42
+    init { result = "OK" }
+}
+
+class A {
+    val x by O::z
+}
+
+fun box(): String {
+    A()
+    return result
+}