[FE 1.0] Don't report UNUSED_* warnings on local properties with delegate

^KT-25527 Fixed

compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedPropertyWithCustomAccessors.fir.kt

@@ -0,0 +1,40 @@
+// ISSUE: KT-25527
+
+import kotlin.reflect.KProperty
+
+fun test_1(delegate: Delegate) {
+    var p1 by delegate
+    p1 = 10
+
+    var p2 by delegate
+    p2++
+
+    var p3 by delegate
+    ++p3
+}
+
+fun test_2() {
+    var p1 = 0
+    p1 = 10
+
+    var p2: Int
+    p2 = 10
+
+    var p3 = 1
+    p3++
+
+    var p4 = 1
+    ++p4
+}
+
+class Delegate {
+    var prop: Int = 0
+
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
+        return prop
+    }
+
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
+        prop = value
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedPropertyWithCustomAccessors.kt

@@ -0,0 +1,40 @@
+// ISSUE: KT-25527
+
+import kotlin.reflect.KProperty
+
+fun test_1(delegate: Delegate) {
+    var p1 by delegate
+    p1 = 10
+
+    var p2 by delegate
+    <!UNUSED_CHANGED_VALUE!>p2++<!>
+
+    var p3 by delegate
+    ++p3
+}
+
+fun test_2() {
+    var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>p1<!> = 0
+    <!UNUSED_VALUE!>p1 =<!> 10
+
+    var <!ASSIGNED_BUT_NEVER_ACCESSED_VARIABLE!>p2<!>: Int
+    <!UNUSED_VALUE!>p2 =<!> 10
+
+    var p3 = 1
+    <!UNUSED_CHANGED_VALUE!>p3++<!>
+
+    var p4 = 1
+    ++p4
+}
+
+class Delegate {
+    var prop: Int = 0
+
+    operator fun getValue(thisRef: Any?, property: KProperty<*>): Int {
+        return prop
+    }
+
+    operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {
+        prop = value
+    }
+}

compiler/testData/diagnostics/tests/controlFlowAnalysis/unusedPropertyWithCustomAccessors.txt

@@ -0,0 +1,14 @@
+package
+
+public fun test_1(/*0*/ delegate: Delegate): kotlin.Unit
+public fun test_2(): kotlin.Unit
+
+public final class Delegate {
+    public constructor Delegate()
+    public final var prop: kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public final operator fun getValue(/*0*/ thisRef: kotlin.Any?, /*1*/ property: kotlin.reflect.KProperty<*>): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public final operator fun setValue(/*0*/ thisRef: kotlin.Any?, /*1*/ property: kotlin.reflect.KProperty<*>, /*2*/ value: kotlin.Int): kotlin.Unit
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}