Fir2Ir: introduce Fir2IrExtensions

This allows us to remove DeclarationStubGenerator from Fir2IrConverter,
thus reducing dependency on descriptor-based code.

compiler/tests-compiler-utils/tests/org/jetbrains/kotlin/codegen/GenerationUtils.kt

@@ -32,6 +32,7 @@ import org.jetbrains.kotlin.config.languageVersionSettings
 import org.jetbrains.kotlin.fir.FirAnalyzerFacade
 import org.jetbrains.kotlin.fir.backend.jvm.FirJvmBackendClassResolver
 import org.jetbrains.kotlin.fir.backend.jvm.FirJvmBackendExtension
+import org.jetbrains.kotlin.fir.backend.jvm.JvmFir2IrExtensions
 import org.jetbrains.kotlin.fir.createSessionForTests
 import org.jetbrains.kotlin.ir.backend.jvm.jvmResolveLibraries
 import org.jetbrains.kotlin.load.kotlin.PackagePartProvider
@@ -113,10 +114,12 @@ object GenerationUtils {
             emptyList(),
             IrGenerationExtension.getInstances(project)
         )
-        val extensions = JvmGeneratorExtensionsImpl(configuration)
-        val (moduleFragment, symbolTable, components) = firAnalyzerFacade.convertToIr(extensions)
+        val (moduleFragment, symbolTable, components) = firAnalyzerFacade.convertToIr(
+            JvmFir2IrExtensions(configuration)
+        )
         val dummyBindingContext = NoScopeRecordCliBindingTrace().bindingContext
 
+        val extensions = JvmGeneratorExtensionsImpl(configuration)
         val codegenFactory = JvmIrCodegenFactory(
             configuration,
             configuration.get(CLIConfigurationKeys.PHASE_CONFIG),

compiler/tests-compiler-utils/tests/org/jetbrains/kotlin/fir/FirAnalyzerFacade.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.diagnostics.DiagnosticReporterFactory
 import org.jetbrains.kotlin.diagnostics.KtDiagnostic
 import org.jetbrains.kotlin.fir.analysis.collectors.FirDiagnosticsCollector
 import org.jetbrains.kotlin.fir.backend.Fir2IrConverter
+import org.jetbrains.kotlin.fir.backend.Fir2IrExtensions
 import org.jetbrains.kotlin.fir.backend.Fir2IrResult
 import org.jetbrains.kotlin.fir.backend.jvm.Fir2IrJvmSpecialAnnotationSymbolProvider
 import org.jetbrains.kotlin.fir.backend.jvm.FirJvmKotlinMangler
@@ -36,7 +37,7 @@ abstract class AbstractFirAnalyzerFacade {
 
     abstract fun runResolution(): List<FirFile>
 
-    abstract fun convertToIr(extensions: GeneratorExtensions): Fir2IrResult
+    abstract fun convertToIr(fir2IrExtensions: Fir2IrExtensions): Fir2IrResult
 }
 
 class FirAnalyzerFacade(
@@ -99,7 +100,7 @@ class FirAnalyzerFacade(
         return collectedDiagnostics!!
     }
 
-    override fun convertToIr(extensions: GeneratorExtensions): Fir2IrResult {
+    override fun convertToIr(fir2IrExtensions: Fir2IrExtensions): Fir2IrResult {
         if (_scopeSession == null) runResolution()
         val mangler = JvmDescriptorMangler(null)
         val signaturer = JvmIdSignatureDescriptor(mangler)
@@ -111,8 +112,9 @@ class FirAnalyzerFacade(
 
         return Fir2IrConverter.createModuleFragment(
             session, _scopeSession!!, firFiles!! + commonFirFiles,
-            languageVersionSettings, mangler, signaturer,
-            extensions, FirJvmKotlinMangler(session), IrFactoryImpl,
+            languageVersionSettings, signaturer,
+            fir2IrExtensions,
+            FirJvmKotlinMangler(session), IrFactoryImpl,
             FirJvmVisibilityConverter,
             Fir2IrJvmSpecialAnnotationSymbolProvider(),
             irGeneratorExtensions