[FIR] Return scope session from LowLevelFirAnalyzerFacade instead of failing

This is needed for proper work of FirScopeDumpHandler for
  low level fir tests

analysis/low-level-api-fir/tests/org/jetbrains/kotlin/analysis/low/level/api/fir/compiler/based/LowLevelFirAnalyzerFacade.kt

@@ -26,7 +26,8 @@ class LowLevelFirAnalyzerFacade(
     val allFirFiles: Map<TestFile, FirFile>,
     private val diagnosticCheckerFilter: DiagnosticCheckerFilter,
 ) : AbstractFirAnalyzerFacade() {
-    override val scopeSession: ScopeSession get() = shouldNotBeCalled()
+    override val scopeSession: ScopeSession
+        get() = ScopeSession()
 
     override fun runCheckers(): Map<FirFile, List<KtDiagnostic>> {
         findSealedInheritors()