[ticket/11334] Properly generate controller URL until paths issue gets fixed

PHPBB3-11334
[ticket/11334] Add a test for the controller helper URL method

PHPBB3-11334
[ticket/11334] Make url helper method public

PHPBB3-11334
[ticket/11334] Make $phpbb_dispatcher global, as done in append_sid test

PHPBB3-11334
[ticket/11334] Remove extraneous period

PHPBB3-11334
[ticket/11334] Include functions.php and fix class name in tests

PHPBB3-11334
[ticket/11334] Expand functionality of helper->url()

Expanded the functionality of helper->url() to support all parameters of
append_sid() itself.

PHPBB3-11334
[ticket/11334] Move unit tests for helper->url() into own file

PHPBB3-11334
[ticket/11334] Use mocks instead of making parameters optional

PHPBB3-11334
[ticket/11334] Fix copyright year in test file

PHPBB3-11334