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
+}

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

@@ -0,0 +1,23 @@
+// WITH_RUNTIME
+val String.foo: String
+    get() = this
+
+abstract class A {
+    abstract val x: String
+
+    val y by x::foo
+}
+
+var storage = "OK"
+
+class B : A() {
+    override var x: String
+        get() = storage
+        set(value) { storage = value }
+}
+
+fun box(): String {
+    val b = B()
+    b.x = "fail"
+    return b.y
+}

compiler/testData/codegen/bytecodeText/optimizedDelegatedProperties/delegateToAnother.kt

@@ -33,6 +33,7 @@ fun local() {
 // Optimized all to direct accesses, with `$delegate` methods generating reflected references on demand:
 // 0 extends kotlin/jvm/internal/MutablePropertyReference[0-2]Impl
 // 0 private final( static)? Lkotlin/reflect/KMutableProperty[0-2]; [xyz]m?\$delegate
+// 2 private final( static)? LC; [xyz]m?\$receiver
 // 0 LOCALVARIABLE [xyz]m? Lkotlin/reflect/KMutableProperty[0-2];
 // 12 static get[XYZ]m?\$delegate