ArC: consider built-in session context during client proxy optimization

- the problem occurs when quarkus-websockets-next and quarkus-undertow
extensions are used at the same time
- fixes quarkusio#46548

independent-projects/arc/processor/src/main/java/io/quarkus/arc/processor/BeanProcessor.java

@@ -591,6 +591,7 @@ private Set<DotName> findSingleContextNormalScopes() {
         Map<DotName, Integer> contextsForScope = new HashMap<>();
         // built-in contexts
         contextsForScope.put(BuiltinScope.REQUEST.getName(), 1);
+        contextsForScope.put(BuiltinScope.SESSION.getName(), 1);
         // custom contexts
         for (Map.Entry<ScopeInfo, List<Function<MethodCreator, ResultHandle>>> entry : beanDeployment
                 .getCustomContexts()