Refact stdlib generator, add support for different backends

[JS IR BE] Runtime fixes
 * Do not generate external declarations for IR BE
 * Move `arrayToString` helper function out of shared JS stdlib
 * Fix arrays type check for IR BE

js/js.translator/testData/box/standardClasses/arraySort.kt

@@ -0,0 +1,20 @@
+// EXPECTED_REACHABLE_NODES: 1284
+package foo
+
+fun test(actual: DoubleArray, expect: DoubleArray): String {
+    for (index in 0 until expect.size) {
+        val expectedElem: Any = expect[index]
+        val actualElem: Any = actual[index]
+        if (expectedElem != actualElem) {
+            return "Content at index $index does not match: $expectedElem != $actualElem"
+        }
+    }
+    return "OK"
+}
+
+fun box(): String {
+    val array = doubleArrayOf(Double.NaN, Double.POSITIVE_INFINITY, Double.NaN, 1.0, Double.NaN, +0.0, Double.NaN, -0.0, Double.NaN, -1.0, Double.NaN, Double.NEGATIVE_INFINITY)
+    array.sort()
+
+    return test(array, doubleArrayOf(Double.NEGATIVE_INFINITY, -1.0, -0.0, +0.0, 1.0, Double.POSITIVE_INFINITY, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN, Double.NaN))
+}