Refactor script infrastructure for easier usage and testability:

- add script annotation for specifying default configuration for a script
- add support for this annotation in the default configurator
- rename configurator accordingly
- add default implementation of the refineConfiguration method
- make property bag class open

libraries/scripting/common/src/kotlin/script/experimental/annotations/scriptAnnotations.kt

@@ -42,3 +42,8 @@ annotation class KotlinScriptEvaluator(
     val evaluator: KClass<out ScriptEvaluator<*>>
 )
 
+@Target(AnnotationTarget.CLASS)
+@Retention(AnnotationRetention.RUNTIME)
+annotation class KotlinScriptDefaultCompilationConfiguration(
+    val compilationConfiguration: KClass<out List<*>> // object or class filled in 0-ary constructor
+)