[atomicfu-K/N] Tests for K/N atomicfu-compiler-plugin

* `nativeTest` task now allows to provide compiler plugins that may be enabled during test compilation
* test sets for JVM and K/N backends are equal

KT-60800 describes all the issues with native tests that were solved in this commit.

Co-authored-by: Dmitriy Dolovov <Dmitriy.Dolovov@jetbrains.com>

Merge-request: KT-MR-11401
Merged-by: Maria Sokolova <maria.sokolova@jetbrains.com>

plugins/atomicfu/atomicfu-compiler/testData/nativeBox/locks/SynchronizedObjectTest.kt

@@ -0,0 +1,21 @@
+import kotlinx.atomicfu.locks.*
+import kotlin.test.*
+
+class SynchronizedObjectTest : SynchronizedObject() {
+
+    fun testSync() {
+        val result = synchronized(this) { bar() }
+        assertEquals("OK", result)
+    }
+
+    private fun bar(): String =
+        synchronized(this) {
+            "OK"
+        }
+}
+
+@Test
+fun box() {
+    val testClass = SynchronizedObjectTest()
+    testClass.testSync()
+}