feat: add getTabs method

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/enhancedtabs/EnhancedTabs.java

@@ -590,7 +590,7 @@ public int getTabCount() {
     return (int) getTabs().count();
   }
 
-  private Stream<Tab> getTabs() {
+  public Stream<Tab> getTabs() {
     return getContent().getItems().stream().map(EnhancedTabs::getTab).filter(Objects::nonNull);
   }