Add Preloaded fonts include in Vartheme BS4

Requested by Razem

Preloaded fonts include in Vartheme so it’s already properly used with preload https://web.dev/preload-critical-assets/

Problem/Motivation

Preload critical assets to improve loading speed
Preload W3C Candidate Recommendation 26 June 2019

Proposed resolution

Follow the new way in the new Drupal default front end theme Olivero
{% include '@olivero/includes/preload.twig' with { olivero_path: olivero_path } only %}

https://git.drupalcode.org/project/drupal/-/blob/9.2.x/core/themes/olive...
https://git.drupalcode.org/project/drupal/-/blob/9.2.x/core/themes/olive...

Should have in Vartheme BS4 and VARTHEM_BS4_SUBTHEME
And the include
{%- include '@vartheme_bs4/includes/preload.twig' with { vartheme_bs4_path: vartheme_bs4_path, html_dir: html_attributes['dir'] } only -%}

{%- include '@VARTHEME_BS4_SUBTHEME/includes/preload.twig' with { VARTHEME_BS4_SUBTHEME_path: VARTHEME_BS4_SUBTHEME_path, html_dir: html_attributes['dir'] } only -%}
Themes should be able to add their preload assets as they like

Remaining tasks

• Change
• Test
• Rrelease

User interface changes

Faster load of face fonts
or could be used for any other preloaded assets

API changes

None

Data model changes

None