Prepare custom code for a new Drupal major version

Problem/Motivation

Current code is not Drupal 10 compatible, we should provide necessary changes in the code before the project fully support Drupal 10

Remaining tasks

1. Drop drupal core 8 support
2. Ensure that core_version_requirement is at least ^9 || ^10
2.1. In some cases it could be ^9.3 || ^10 or ^9.4 || ^10 (depends on the core services/changes used in the code), so choose the minimum core version wisely.
3. Follow this article to scan the code and replace deprecation https://www.drupal.org/docs/upgrading-drupal/prepare-major-upgrade/depre... →
3.1. Apply the changes for theme template files.
4. jquery.once is handled in a seprated issue 📌 Replace jquery.once by core/once Fixed