Add entity id and type to link array passed to sitemap generator in order to make link alter hook more usable

Remove options variable (containing language objects etc) from array passed to sitemap generator to save resources

Clean up a few classes, prevent simple_sitemap service from loading xml sitemap chunks from DB on every initialization

Fix error introduced in b28b57b3 where sitemap only partially gets generated when max links settings are too low

Issue #2713661 by ec0g: Fatal error: Call to undefined function Drupal\simple_sitemap\Batch::finishBatch()

Adjusting schema definition, improving some field descriptions, fixing not being able to add 0 as link priority.

Fixing wrong language codes in custom url generation, fixing wrong date format in sitemap, improving duplicate prevention and annotating some code.