Refactor script definitions loading

Make ScriptDefinitionProvider an interface
    and provide different implementation for cli and IDEA
Rework ide extension point to a simpler interface (ScriptDefinitionContributor)
Move template loading logic into a top level function
Allow script definitions to be reloaded in IDE

libraries/tools/kotlin-script-util/src/test/kotlin/org/jetbrains/kotlin/script/util/ScriptUtilIT.kt

@@ -115,7 +115,7 @@ done
             suppressOutput: Boolean = false
     ): Class<*>? =
             compileScriptImpl("src/test/resources/scripts/" + scriptFileName,
-                              KotlinScriptDefinitionFromAnnotatedTemplate(scriptTemplate, null, null, environment), suppressOutput)
+                              KotlinScriptDefinitionFromAnnotatedTemplate(scriptTemplate, environment), suppressOutput)
 
     private fun compileScriptImpl(
             scriptPath: String,