Mark interfaces as API

[sivaschenko]

The following interfaces should be marked as API in future-develop branch

1. magento2-page-builder/app/code/Magento/PageBuilder/Api/Data/TemplateInterface.php
2. magento2-page-builder/app/code/Magento/PageBuilder/Api/Data/TemplateSearchResultsInterface.php
3. magento2-page-builder/app/code/Magento/PageBuilder/Api/TemplateRepositoryInterface.php
4. magento2-page-builder/app/code/Magento/PageBuilder/Model/Catalog/Sorting/OptionInterface.php
5. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/AttrInterface.php
6. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/CharacterDataInterface.php
7. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/CommentInterface.php
8. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/DocumentFragmentInterface.php
9. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/DocumentInterface.php
10. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/DocumentTypeInterface.php
11. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/ElementInterface.php
12. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/HtmlCollectionInterface.php
13. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/HtmlDocumentInterface.php
14. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/NodeInterface.php
15. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/NodeListInterface.php
16. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/PropertyAttributeInterface.php
17. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/StringMapInterface.php
18. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/TextInterface.php
19. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/TokenListInterface.php
20. magento2-page-builder/app/code/Magento/PageBuilder/Model/Dom/Adapter/XmlDocumentInterface.php
21. magento2-page-builder/app/code/Magento/PageBuilder/Model/Stage/RendererInterface.php

[m2-assistant]

Hi @sivaschenko. Thank you for your report.
To help us process this issue please make sure that you provided sufficient information.

Please, add a comment to assign the issue: @magento I am working on this

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[Usik2203]

@magento I am working on this

[gabrieldagama]

These changes should target develop branch.