[Test] Migrate AbstractDiagnosticsWithJdk15Test to new infrastructure

compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/builders/LanguageVersionSettingsBuilder.kt

@@ -67,6 +67,7 @@ class LanguageVersionSettingsBuilder {
             analysisFlag(JvmAnalysisFlags.jvmDefaultMode, directives.singleOrZeroValue(LanguageSettingsDirectives.JVM_DEFAULT_MODE)),
             analysisFlag(JvmAnalysisFlags.inheritMultifileParts, trueOrNull(LanguageSettingsDirectives.INHERIT_MULTIFILE_PARTS in directives)),
             analysisFlag(JvmAnalysisFlags.sanitizeParentheses, trueOrNull(LanguageSettingsDirectives.SANITIZE_PARENTHESES in directives)),
+            analysisFlag(JvmAnalysisFlags.enableJvmPreview, trueOrNull(LanguageSettingsDirectives.ENABLE_JVM_PREVIEW in directives)),
 
             analysisFlag(AnalysisFlags.explicitApiVersion, trueOrNull(apiVersion != null)),
         )

compiler/test-infrastructure/tests/org/jetbrains/kotlin/test/directives/LanguageSettingsDirectives.kt

@@ -67,6 +67,8 @@ object LanguageSettingsDirectives : SimpleDirectivesContainer() {
         description = "Enables corresponding analysis flag (JvmAnalysisFlags.sanitizeParentheses)"
     )
 
+    val ENABLE_JVM_PREVIEW by directive("Enable JVM preview features")
+
     // --------------------- Utils ---------------------
 
     fun parseApiVersion(versionString: String): ApiVersion = when (versionString) {