Do not force loading all kt-files inside LazyPackageDescriptor constructor

Effectively it leads to all stubs being built for any once used package

The idea is that they only were used for FILE_TO_PACKAGE_FRAGMENT
that is mostly read in backend and rarely in the IDE, so we can replace
its usages with searching through related package-fragments

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/ModuleGenerator.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.ir.declarations.impl.IrModuleFragmentImpl
 import org.jetbrains.kotlin.ir.util.ExternalDependenciesGenerator
 import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.lazy.descriptors.findPackageFragmentForFile
 
 class ModuleGenerator(override val context: GeneratorContext) : Generator {
     fun generateModuleFragment(ktFiles: Collection<KtFile>): IrModuleFragment =
@@ -63,9 +64,9 @@ class ModuleGenerator(override val context: GeneratorContext) : Generator {
 
     private fun createEmptyIrFile(ktFile: KtFile): IrFileImpl {
         val fileEntry = context.sourceManager.getOrCreateFileEntry(ktFile)
-        val packageFragmentDescriptor = getOrFail(BindingContext.FILE_TO_PACKAGE_FRAGMENT, ktFile)
+        val packageFragmentDescriptor = context.moduleDescriptor.findPackageFragmentForFile(ktFile)!!
         val irFile = IrFileImpl(fileEntry, packageFragmentDescriptor)
         context.sourceManager.putFileEntry(irFile, fileEntry)
         return irFile
     }
-}
+}