kotlinx.atomicfu compiler plugin for JS_IR backend (#4581)

* kotlinx.atomicfu compiler plugin for JS_IR

Support transformations of atomic operations introduced by the kotlinx.atomicfu library for the JS_IR backend. Compiler plugin is applied externally by the kotlinx.atomicfu gradle plugin.

* Apply compiler plugin for JS platform only

* New plugin test structure

* testGroupOutputDirPrefix changed

plugins/atomicfu/atomicfu-compiler/testData/box/LockFreeQueueTest.kt

@@ -0,0 +1,55 @@
+import kotlinx.atomicfu.*
+import kotlin.test.*
+
+class LockFreeQueueTest {
+    fun testBasic() {
+        val q = LockFreeQueue()
+        check(q.dequeue() == -1)
+        q.enqueue(42)
+        check(q.dequeue() == 42)
+        check(q.dequeue() == -1)
+        q.enqueue(1)
+        q.enqueue(2)
+        check(q.dequeue() == 1)
+        check(q.dequeue() == 2)
+        check(q.dequeue() == -1)
+    }
+}
+
+// MS-queue
+public class LockFreeQueue {
+    private val head = atomic(Node(0))
+    private val tail = atomic(head.value)
+
+    private class Node(val value: Int) {
+        val next = atomic<Node?>(null)
+    }
+
+    public fun enqueue(value: Int) {
+        val node = Node(value)
+        tail.loop { curTail ->
+            val curNext = curTail.next.value
+            if (curNext != null) {
+                tail.compareAndSet(curTail, curNext)
+                return@loop
+            }
+            if (curTail.next.compareAndSet(null, node)) {
+                tail.compareAndSet(curTail, node)
+                return
+            }
+        }
+    }
+
+    public fun dequeue(): Int {
+        head.loop { curHead ->
+            val next = curHead.next.value ?: return -1
+            if (head.compareAndSet(curHead, next)) return next.value
+        }
+    }
+}
+
+fun box(): String {
+    val testClass = LockFreeQueueTest()
+    testClass.testBasic()
+    return "OK"
+}