Rename KClass.properties and extensionProperties: prepend 'member'

To better emphasize the fact that all returned properties require an instance
of the class they are declared in. Another issue was that
'Some::class.extensionProperties' was sometimes incorrectly perceived as
"get all extension properties available on the class Some"

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

@@ -14,7 +14,7 @@ class A(param: String) {
 fun box(): String {
     val klass = javaClass<A>().kotlin
 
-    val props = klass.properties
+    val props = klass.memberProperties
 
     val names = props.map { it.name }.toSortedList()
     assert(names == listOf("anyVar", "int", "string")) { "Fail names: $props" }