tests: Copy stdlib tests from Kotlin/JVM

This patch copies Kotlin/JVM stdlib tests (libraries/stdlib/test)
excepting ones with explicit java dependencies. It also transforms
the tests to use them as box-tests.

backend.native/tests/external/stdlib/collections/CollectionTest/sum.kt

@@ -0,0 +1,11 @@
+import kotlin.test.*
+import kotlin.comparisons.*
+
+fun box() {
+    expect(0) { arrayListOf<Int>().sum() }
+    expect(14) { listOf(2, 3, 9).sum() }
+    expect(3.0) { listOf(1.0, 2.0).sum() }
+    expect(3000000000000) { arrayListOf<Long>(1000000000000, 2000000000000).sum() }
+    expect(3.0.toFloat()) { arrayListOf<Float>(1.0.toFloat(), 2.0.toFloat()).sum() }
+    expect(3.0.toFloat()) { sequenceOf<Float>(1.0.toFloat(), 2.0.toFloat()).sum() }
+}