[feature/oauth] Fix ucp_auth_link headers/footers

PHPBB3-11673
[feature/oauth] Default auth_link into UCP_PROFILE not UCP_MAIN

PHPBB3-11673
[feature/oauth] Start building the template

PHPBB3-11673
[feature/oauth] Add method to return necessary data for auth_link

PHPBB3-11673
[feature/oauth] More template work

PHPBB3-11673