Bug fixes

* Issue #3122628 by VladimirAus: PHPCS and upgrade status warnings fixes
* Issue #3009382 by VladimirAus, neclimdul: CSRF on delete url
* Issue #3117996 by neelam_wadhwani, VladimirAus: All dependencies must be prefixed with the project name
* Issue #3117989 by prabha1997, VladimirAus: Drupal 9: remove deprecated function calls
* Added tests, removed features context.
* Added code review suggestions.

Realised the URL to URI fix didn't make the last tag - whoops!

Fixed one small bug with the URI alter - wrong variable name passed.

Applied patches from: -

Fixes JS error on Drupal side: https://www.drupal.org/project/bootstrap_storybook/issues/3121498
Adds documentation for subtheme updates
Defines composer.json and theme dependencies

Solves issues

1. Issue #3122535 by prabha1997, Drupal 9 Readiness
2. Issue #3122532 by prabha1997, t() calls should be avoided in classes, use dependency injection and $this->t() instead
3. Issue #3122527 by prabha1997, All dependencies must be prefixed with the project name, for example "drupal:"