Implement codegen for bound class reference expressions

- Inline the usage of ExpressionCodegen#generateClassLiteralReference into
  ClosureCodegen, simplify
- Support DoubleColonLHS.Expression in generateClassLiteralReference
- Substantially simplify KClass.java intrinsic by reusing
  generateClassLiteralReference

 #KT-13075 Fixed
 #KT-12995 In Progress

compiler/testData/codegen/box/classLiteral/bound/simple.kt

@@ -0,0 +1,5 @@
+fun box(): String {
+    val x: CharSequence = ""
+    val klass = x::class
+    return if (klass == String::class) "OK" else "Fail: $klass"
+}