Bug fix: Nonexistent base_path variable in html.html.twig

[Adnan-cds]

The base_path Twig variable used in html.html.twig doesn't actually exist. This fix adds the localgov_front_page_default_lang variable as a replacement. As an added bonus, localgov_front_page_default_lang can be modified through PathProcessors plugins.

[stephen-cox]

The base_path variable looks to be working fine on the demo site: view-source:https://demo.localgovdrupal.org/. Are these new variables going to be used for anything else?

Just to add, localgov_theme is about to become deprecated in favour of localgov_base

[Adnan-cds]

Hi Steve,
Thanks for looking into this. Sorry, I should have added reproduction steps:

$ mkdir -p /tmp/html/
$ cd /tmp/html/
$ composer create-project --stability dev localgovdrupal/localgov-project
$ cd localgov-project/
$ > web/sites/default/settings.lando.php
$ ./bin/drush site:install --yes --db-url=sqlite://sites/default/files/.ht.sqlite localgov
$ php -S localhost:8888

view-source:http://localhost:8888/web/ should expose the problem with the non-existent favicon path. You can also check the presence of the favicon in the browser's title bar.

The reason base_path has no existence within html.html.twig is because neither _template_preprocess_default_variables() nor template_preprocess_html() declares it :(

[stephen-cox]

I see the issue now. Happy to approve

[Adnan-cds]

Thanks Steve. Merging...