Add support for Google news sitemaps

I just needed the Google News Support and having to solution, contributing or adding the Generators to the project.
I post also here a patch for the 4.2.2 release - for those willing to test over the 4.2.2 release and not 4.x.

Proposed resolution

• SitemapNewsGenerator: Handles the Sitemap schema and elements creation according to Google News specifications.
• NewsUrlGenerator: Handles element construction path required by the Sitemap News Generator.
• hook_simple_sitemap_entity_process: Added the Sitemap parameter to this hook to allow filtering by Sitemap type.

Steps to reproduce

1. Create a new Sitemap Type using the Google News Generator
   
2. Create a new Sitemap that uses the Google News type created in step 1
   

Remaining tasks

• Discuss and iterate over the initial proposal and reach consensus
• Update the Issue Summary
• Implement test coverage
• Merge

User interface changes

A new details section appears for the News Brand Name setting required by Google News.
See https://developers.google.com/search/docs/crawling-indexing/sitemaps/new... for information about the <news:name> element.

API changes

hook_simple_sitemap_entity_process: Added the Sitemap parameter to this hook to allow filtering by Sitemap.
This change could be separated into another issue if preferred.

Well, it seems this feature will be killed by Google itself (https://support.google.com/news/publisher-center/answer/15898024).
I would suggest to not merge this MR and close it.

hook_simple_sitemap_entity_process: Added the Sitemap parameter to this hook to allow filtering by Sitemap.

This will be added before the next release here: ✨ Discard adding if rabbit hole setting is active Needs review

Well, it seems this feature will be killed by Google itself (https://support.google.com/news/publisher-center/answer/15898024).
I would suggest to not merge this MR and close it.

This is a good effort, it's a pity Google is killing it (but what do you expect from Google).

I'd recommend adding the functionality to the Simple XML Sitemap news → module which is currently not being maintained. This way we don't take on the burden of maintaining code that becomes unsupported upstream, but people can still take advantage.

I'd recommend adding the functionality to the Simple XML Sitemap news module which is currently not being maintained. This way we don't take on the burden of maintaining code that becomes unsupported upstream, but people can still take advantage.

In fact let me move this issue to that module's queue - maybe something will happen.