[ticket/11450] Remove unused $db and $phpEx from metadata_manager construct()

PHPBB3-11450
[ticket/11450] Sort parameters alphabetically

PHPBB3-11450
[ticket/11450] Fix doc blocks and add missing class var $config

PHPBB3-11450
[ticket/11450] Fix all instances of phpbb_extension_metadata_manager

PHPBB3-11450
[ticket/11450] Test the extensions details page in ACP Customise Tab

PHPBB3-11450
[ticket/11450] Add test for unexisting composer.json

PHPBB3-11450
[ticket/11450] Require db_tools file to be included

PHPBB3-11450
[ticket/11450] Fix tests class name

PHPBB3-11450
[ticket/11450] Add new line at end of file

PHPBB3-11450
[ticket/11450] Move mocked class into mock/metadata_manager.php

PHPBB3-11450
[ticket/11450] Use helpers to copy/remove files

PHPBB3-11450
[ticket/11450] Limit scopes of filters and add better docs

PHPBB3-11450
Merge PR #1308 branch 'nickvergessen/ticket/11450' into develop

# By Joas Schilling
# Via Joas Schilling
* nickvergessen/ticket/11450:
  [ticket/11450] Limit scopes of filters and add better docs
  [ticket/11450] Use helpers to copy/remove files
  [ticket/11450] Move mocked class into mock/metadata_manager.php
  [ticket/11450] Add new line at end of file
  [ticket/11450] Fix tests class name
  [ticket/11450] Require db_tools file to be included
  [ticket/11450] Add test for unexisting composer.json
  [ticket/11450] Test the extensions details page in ACP Customise Tab
  [ticket/11450] Fix all instances of phpbb_extension_metadata_manager
  [ticket/11450] Fix doc blocks and add missing class var $config
  [ticket/11450] Sort parameters alphabetically
  [ticket/11450] Remove unused $db and $phpEx from metadata_manager construct()