[ticket/12664] Refactor develop/migration_tips.php into a console command.

PHPBB3-12664
Merge pull request #2569 from bantu/ticket/12664

[ticket/12664] Refactor develop/migration_tips.php into a console command.

* bantu/ticket/12664:
  [ticket/12664] Refactor develop/migration_tips.php into a console command.
[ticket/12508] Remove extension manager from finder

PHPBB3-12508
[ticket/12508] Fix usages of the finder

PHPBB3-12508
[ticket/12508] Move \phpbb\extension\finder to \phpbb\finder

PHPBB3-12508
[ticket/12508] Fix class doc block

PHPBB3-12508
[ticket/12508] Only take a list of names for set_extensions()

PHPBB3-12508
[ticket/12508] Add a unit test for set_extensions()

PHPBB3-12508
[ticket/12508] Add new line to separate the if and foreach better

PHPBB3-12508
[ticket/12508] Fix doc block

PHPBB3-12508
[ticket/12508] Ignore extensions in migration_tips dev tool

PHPBB3-12508
[ticket/12687] Add a constant to display the load time without DEBUG

PHPBB3-12687
[ticket/12687] Display the explain link only when DEBUG is set

PHPBB3-12687
[ticket/12687] Rename DISPLAY_LOAD_TIME to PHPBB_DISPLAY_LOAD_TIME

PHPBB3-12687
Merge remote-tracking branch 'github-nickvergessen/ticket/12508' into develop-ascraeus

* github-nickvergessen/ticket/12508:
  [ticket/12508] Ignore extensions in migration_tips dev tool
  [ticket/12508] Fix doc block
  [ticket/12508] Add new line to separate the if and foreach better
  [ticket/12508] Add a unit test for set_extensions()
  [ticket/12508] Only take a list of names for set_extensions()
  [ticket/12508] Fix class doc block
  [ticket/12508] Move \phpbb\extension\finder to \phpbb\finder
  [ticket/12508] Fix usages of the finder
  [ticket/12508] Remove extension manager from finder
[ticket/12483] Allow to setup extensions before database and functional tests

PHPBB3-12483
[ticket/12483] Add a .sh that moves an extension in place

PHPBB3-12483
[ticket/12483] Move schema files into tmp/ and only copy them when needed

PHPBB3-12483
[ticket/12483] Require the extension manager class

PHPBB3-12483
[ticket/12483] Close database connection when tearDown() is called

Similar to phpbb_database_test_case::tearDown()

PHPBB3-12483