[K/Wasm] Introduce JsBigInt type

libraries/stdlib/wasm/js/src/kotlin/js/JsBigInt.kt

@@ -0,0 +1,19 @@
+/*
+ * Copyright 2010-2023 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
+
+import kotlin.wasm.internal.*
+import kotlin.wasm.internal.JsPrimitive
+
+/** JavaScript primitive bigint */
+@JsPrimitive("bigint")
+public external class JsBigInt internal constructor() : JsAny
+
+public fun JsBigInt.toLong(): Long =
+    externRefToKotlinLongAdapter(this)
+
+public fun Long.toJsBigInt(): JsBigInt =
+    kotlinLongToExternRefAdapter(this)