[ticket/11362] Correctly sanitise the directory path

We need to correctly remove ../ form the path if possible by removing the
previous folder aswell. Otherwise the finder is unable to locate /adm/style
directories in extensions as he is looking for /adm/../adm/style instead.

PHPBB3-11362
[ticket/11362] Add unit test for ../ in directory paths

PHPBB3-11362
[ticket/11485] add columns to styles table during updating schema before
updating the data

PHPBB3-10485
[ticket/11485] add revert_schema for the updated columns

PHPBB3-11485
[ticket/10844] Add phpbb_root_path to phpbb_style_extension_path_provider

The phpbb_root_path needs to be removed from the style path, before giving
the path to the finder, because the finder prepends it later again and is
therefor unable to find style files when the root path is not ./

PHPBB3-10844
[ticket/10844] Make sure ext_path has no trailing slash

PHPBB3-10844
[ticket/10844] Add unit tests for different root_paths

PHPBB3-10844
[ticket/11362] Move phpbb_clean_path into a simple filesystem service

PHPBB3-11362
[ticket/11362] Use new filesystem class in finder

PHPBB3-11362
[ticket/11362] Replace other calls to phpbb_clean_path

Need to instantiate the object manually here, as the container is not yet
set up.

PHPBB3-11362
[ticket/11362] Extension manager depends on filesystem

PHPBB3-11362
[ticket/11362] Fix service description of finder

PHPBB3-11362
[ticket/10966] Introduce MySQL base class

PHPBB3-10966
[ticket/11362] Add compatibility function phpbb_clean_path() again

The function first depends on the container, but also works without it and
without autoload. The reason for this is, it might be used before that
stuff is set up, like it has been in our common.php

PHPBB3-11362
Merge remote-tracking branch 'nickvergessen/ticket/10966' into develop

* nickvergessen/ticket/10966:
  [ticket/10966] Introduce MySQL base class
[ticket/11501] Assert the variables instead of fail() with the condition

PHPBB3-11501
[ticket/11501] Remove test_ prefix from data provider methods

PHPBB3-11501
Merge remote-tracking branch 'nickvergessen/ticket/11501' into develop

* nickvergessen/ticket/11501:
  [ticket/11501] Remove test_ prefix from data provider methods
  [ticket/11501] Assert the variables instead of fail() with the condition
[ticket/10966] Introduce MSSQL base class for native and ODBC

PHPBB3-10966
Merge remote-tracking branch 'nickvergessen/ticket/10966-2' into develop

* nickvergessen/ticket/10966-2:
  [ticket/10966] Introduce MSSQL base class for native and ODBC