[ticket/13238] Add an interface for \phpbb\db\tools

PHPBB3-13238
[ticket/13238] Inherit docs

PHPBB3-13238
[ticket/13238] Always require the interface when possible

PHPBB3-13238
[ticket/13238] Add array implementation of tools so we can check sql_*_exists

PHPBB3-13238
[ticket/13238] Use array implementation of db\tools to generate the schema

PHPBB3-13238