Bug fixes

• Implementations of Implements hook_form_FORM_ID_alter().
• Using placeholders with t() for variables.

Issue #3003711 by doublealpha: Remove Field UI dependency

Issue #3086280 by graker: No HTML filtering in labels

Issue #3023842 by Gogowitsch, el1_1el: Empty option: add setting to supply user-defined string

Issue #3133802 by ankithashetty: Add core_version_requirement for Drupal 9 compatibility

• Undergoing pareview.sh; Deleted LICENSE.txt; Unused variable $config, $output_d, $output_t, $host.
• Fixing EventSubscriber Firewall between white and buffer.
• Adding service injection into mailController.

Add secondary checksum for GST number

Please see UPDATE.md file in the Droopler directory for migration instructions.