Scripting: avoid creating multiple PSIs for every imported script

#KT-53009 fixed
#KT-42810 should be possible now too, but more testing is needed
#KT-42101 can also be addressed now, but first the serialization
 of the imported scripts property should be solved

libraries/scripting/jvm-host-test/test/kotlin/script/experimental/jvmhost/test/ScriptingHostTest.kt

@@ -373,7 +373,7 @@ class ScriptingHostTest : TestCase() {
         }
         val res = BasicJvmScriptingHost().eval(script.toScriptSource(), compilationConfiguration, null)
         assertTrue(res is ResultWithDiagnostics.Failure)
-        val report = res.reports.find { it.message.startsWith("Source file or directory not found") }
+        val report = res.reports.find { it.message.startsWith("Imported source file not found") }
         assertNotNull(report)
         assertEquals("script.kts", report?.sourcePath)
     }