Move "show all config" from DarkConsole to /config/

Summary:
Currently, we have a "config" panel in DarkConsole. It's useful to have a table of all effective config values, but it doesn't need to be in DarkConsole. Move it to Config instead. Basically:

• You don't need to activate DarkConsole to see it anymore;
• now visible only to admins;
• respects config mask/hide;
• somewhat prettier;
• links to config edit;
• no longer ships down on every DarkConsole request with a giant table of rarely-used data.

Test Plan: Looked at the table. Looked at lack of table in darkconsole.

Reviewers: codeblock, btrahan

Reviewed By: codeblock

CC: aran

Maniphest Tasks: T2255

Differential Revision: https://secure.phabricator.com/D4473