[FIR2IR] Rename entrypoint function of Fir2IrConverter

Originally it was named createModuleFragmentWithSignaturesIfNeeded, because
  there was a counterpart `...WithoutSignatures`. Now that function has
  gone and there is only one entrypoint left

compiler/fir/entrypoint/src/org/jetbrains/kotlin/fir/pipeline/convertToIr.kt

@@ -45,7 +45,7 @@ data class ModuleCompilerAnalyzedOutput(
         visibilityConverter: Fir2IrVisibilityConverter,
         kotlinBuiltIns: KotlinBuiltIns,
     ): Fir2IrResult {
-        return Fir2IrConverter.createModuleFragmentWithSignaturesIfNeeded(
+        return Fir2IrConverter.createIrModuleFragment(
             session, scopeSession, fir,
             fir2IrExtensions, fir2IrConfiguration,
             irMangler, IrFactoryImpl, visibilityConverter,