[ticket/13034] Fix the route generated for the frontend not in the phpbb root

PHPBB3-13034
[ticket/13034] Fix unit tests

PHPBB3-13034
[ticket/12963] Fix the list of migrations in database_update.php

Without this patch the finder grab all the class available in the ext
folder and not only the migrations. This change is backported for the one
done before to the cli tool db:migrate. (see the commit
3420f8f3201ac337434f73ee00bda6df7b378212)

PHPBB3-12963
[ticket/12963] Don't use static var in \extension\base\get_migration_file_list

The static var was global to all instance of \phpbb\base and so if two
different instances (for two different extensions) were created by the
same script they shared the same migrations list.

PHPBB3-12963
[ticket/12963] Load extensions migrations from /migration

PHPBB3-12963
[ticket/12963] Add unit tests

PHPBB3-12963
[ticket/13056] Move the arguments of the request class to the DI

PHPBB3-13056
[ticket/13061] Replace the service event.subscriber_loader by a compiler pass

PHPBB3-13061
[ticket/13062] Add viewforum.php core event to modify topic ids sql query

Event request: http://area51.phpbb.com/phpBB/viewtopic.php?f=111&t=45383

PHPBB3-13062
[ticket/13064] Validate the migrations provided to migrator::set_migrations()

PHPBB3-13064
[ticket/13034] Use utf8_basename

PHPBB3-13034
[ticket/13018] Remove duplicate logic in confirm box and alert box handling.

This ensures a more consistent handling of the various closing/opening actions
and fixes some bugs where certain event handlers are not turned off in certain
instances.

PHPBB3-13018
[ticket/13018] Reduce the delta further.

The callback does not actually do anything when cancelling the confirmation
box so we can avoid calling it altogether when cancel is clicked.

PHPBB3-13018
[ticket/13018] Do not handle events in close function.

PHPBB3-13018
[ticket/13018] Clean up and fix some logic.

PHPBB3-13018
[ticket/13034] Add comment

PHPBB3-13034
Merge pull request #2943 from Nicofuma/ticket/13056

[ticket/13056] Move the arguments of the request class to the DI

* Nicofuma/ticket/13056:
  [ticket/13056] Move the arguments of the request class to the DI
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13056] Move the arguments of the request class to the DI
Merge pull request #2958 from prototech/ticket/13018

[ticket/13018] Remove duplicate logic in confirm box and alert box handling.

* prototech/ticket/13018:
  [ticket/13018] Clean up and fix some logic.
  [ticket/13018] Do not handle events in close function.
  [ticket/13018] Reduce the delta further.
  [ticket/13018] Remove duplicate logic in confirm box and alert box handling.
Merge branch 'develop-ascraeus' into develop

* develop-ascraeus:
  [ticket/13018] Clean up and fix some logic.
  [ticket/13018] Do not handle events in close function.
  [ticket/13018] Reduce the delta further.
  [ticket/13018] Remove duplicate logic in confirm box and alert box handling.