FIR: add raw fir building delegate expression test

compiler/fir/raw-fir/psi2fir/testData/rawBuilder/declarations/delegates.kt

@@ -0,0 +1,13 @@
+import kotlin.properties.ReadWriteProperty
+import kotlin.reflect.KProperty
+
+val x: Int by lazy { 1 + 2 }
+
+val delegate = object: ReadWriteProperty<Any?, Int> {
+    override fun getValue(thisRef: Any?, property: KProperty<*>): Int = 1
+    override fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) {}
+}
+
+val value by delegate
+
+var variable by delegate