[ticket/11942] Delete post/topic reason should be added to logs

https://tracker.phpbb.com/browse/PHPBB3-11942

PHPBB3-11942
[ticket/11942] Adding the reason to hard deleted topic/post

PHPBB3-11942
[ticket/11942] Change the formulation

PHPBB3-11942
[ticket/11942] Edits messages

PHPBB3-11942
[ticket/10899] Using Delete All in log viewer with keyword search

https://tracker.phpbb.com/browse/PHPBB3-10899

PHPBB3-10899
[ticket/10899] Refactoring in \phpbb\log\log_interface

PHPBB3-10899
[ticket/10899] Typo

PHPBB3-10899
[ticket/10899] Remove extra ';'

PHPBB3-10899
[ticket/11942] Always display delete reason

PHPBB3-11942
[ticket/11942] Apply the modifications to subsilver

PHPBB3-11942
[ticket/11942] Remove useless IF in templates

PHPBB3-11942
[ticket/11942] Don't show the checkbox if the post is already soft-deleted

PHPBB3-11942
[ticket/10899] Get $phpbb_log from the container

PHPBB3-10899
[ticket/10899] Add unit tests

PHPBB3-10899
[ticket/10899] Fix typo in the class name

PHPBB3-10899
[ticket/10899] Remove trailing ;

PHPBB3-10899
[ticket/10899] Add event core.delete_log

PHPBB3-10899
[ticket/10899] Use isset($field_value['IN'])

PHPBB3-10899
[ticket/11467] Add language variables for extension exception messages

Remove hard-coded messages and add language variables for extension
exception messages.

PHPBB3-11467
[ticket/11467] Add language variables to tests

Convert the hardcoded strings to language variables.

PHPBB3-11467