Rearrange stdlib unit tests across packages.

Rearrange JS stdlib unit tests.

libraries/stdlib/test/language/EscapedTestNamesTest.kt

@@ -0,0 +1,17 @@
+package test.language
+
+import org.junit.Test as test
+import kotlin.test.*
+
+class EscapedTestNamesTest {
+
+    @test fun `strings equal`() {
+        val actual = "abc"
+        assertEquals("abc", actual)
+    }
+
+    @test fun `numbers equal`() {
+        val actual = 5
+        assertEquals(5, actual)
+    }
+}