Implement KClass.getProperties()

#KT-6570 In Progress

compiler/testData/codegen/boxWithStdlib/reflection/properties/getPropertiesMutableVsReadonly.kt

@@ -0,0 +1,20 @@
+import kotlin.reflect.jvm.kotlin
+import kotlin.reflect.KMutableMemberProperty
+
+class A(val readonly: String) {
+    var mutable: String = "before"
+}
+
+fun box(): String {
+    val props = javaClass<A>().kotlin.getProperties()
+    val readonly = props.single { it.name == "readonly" }
+    assert(readonly !is KMutableMemberProperty<A, *>) { "Fail 1: $readonly" }
+    val mutable = props.single { it.name == "mutable" }
+    assert(mutable is KMutableMemberProperty<A, *>) { "Fail 2: $mutable" }
+
+    val a = A("")
+    mutable as KMutableMemberProperty<A, String>
+    assert(mutable[a] == "before") { "Fail 3: ${mutable.get(a)}" }
+    mutable[a] = "OK"
+    return mutable.get(a)
+}