[ticket/11975] Add ACP link next to MCP link in header

PHPBB3-11975
[ticket/11975] Make link text shorter on smaller resolutions

PHPBB3-11975
[ticket/11975] Change shortened ACP/MCP label to Administer/Moderate

Also utilizing the new data-responsive-text attribute

PHPBB3-11975
[ticket/11975] Remove copy/paste fail, fix tests

PHPBB3-11975
Merge pull request #1826 from imkingdavid/ticket/11975

[ticket/11975] Add ACP link next to MCP link in header