test: override ContextualStorageManager in UiContextTest (#132)

Since latest changes in Quarkus, scope annotated beans are discovered
even if the scope is not registered.
This change marks the ContextualStorageManager used in UiContextTest as
an alternative to the VaadinSessionScoped ContextualStorageManager bean
defined in UIScopedContext, preventing AmbiguousResolutionException in
tests.

Fixes #131

runtime/src/test/java/com/vaadin/quarkus/context/UiContextTest.java

@@ -16,7 +16,9 @@
 
 package com.vaadin.quarkus.context;
 
+import jakarta.annotation.Priority;
 import jakarta.enterprise.context.Dependent;
+import jakarta.enterprise.inject.Alternative;
 import jakarta.enterprise.inject.spi.BeanManager;
 
 import java.lang.reflect.Proxy;
@@ -55,6 +57,8 @@ BeanManager getBeanManager() {
 
     @Dependent
     @Unremovable
+    @Alternative
+    @Priority(1)
     public static class TestContextualStorageManager
             extends UIScopedContext.ContextualStorageManager {