Abstract script compiled module implementation used in saving/caching

removes classloading problem when main-kts is loaded from a CL
without scripting compiler.
Also relax dependencies collection on saving to a jar and hide redundant
logging.
Running main.kts script via a run configuration works now.
#KT-37765 fixed

plugins/scripting/scripting-compiler-impl/src/org/jetbrains/kotlin/scripting/definitions/ScriptiDefinitionsFromClasspathDiscoverySource.kt

@@ -341,7 +341,7 @@ private fun loadScriptDefinition(
                 ScriptDefinition.FromLegacyTemplate(hostConfiguration, cls.kotlin)
             }
         messageReporter(
-            ScriptDiagnostic.Severity.INFO,
+            ScriptDiagnostic.Severity.DEBUG,
             "Added script definition $template to configuration: name = ${def.name}"
         )
         return def