improve lib and add template for libs

lib/src/commonTest/kotlin/LibraryTest.kt

@@ -0,0 +1,14 @@
+/*
+ * This Kotlin source file was generated by the Gradle 'init' task.
+ */
+package project_group.project_name.lib
+
+import kotlin.test.Test
+import kotlin.test.assertTrue
+
+class LibraryTest {
+    @Test fun testSomeLibraryMethod() {
+        val classUnderTest = Library()
+        assertTrue(classUnderTest.someLibraryMethod(), "someLibraryMethod should return 'true'")
+    }
+}