[JS IR] Generate jsClass function inside the compiler instead of relying on declaration inside stdlib

We want to make its type parameter reified to do it we have to make it inline and non-external.
But we don't want to inline it in call sites and want prevent using it anywhere except places generated by the compiler.
In user code, including stdlib, we should use `K::class.js` instead.
Separately we have to intrinsify `K::class.js` to reduce overhead.

libraries/stdlib/js-ir/src/kotlin/jsClass_js-ir.kt

@@ -1,8 +0,0 @@
-/*
- * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
- * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
- */
-
-package kotlin.js
-
-internal inline fun <reified T : Any> jsClass(): JsClass<T> = throw NotImplementedError("Implemented as intrinsic")