Remove the theme supports check when deciding post format rewrites

[nacin]

Currently, when registering the post_format taxonomy, we check current_theme_supports('post-formats').

This introduces a problem in canonical when formats are not supported, where /type/aside/ redirects to /type/aside/?post_format=aside. In this specific case, Mark was actually registering support on init 10, which was too late for the core taxonomies at init 0. (Would need to happy on after_setup_theme.)

Instead, we should always support rewriting, and let the query 404 the page as appropriate. Thus, /type/aside/ will 404 when there are no asides, whether formats are enabled or not, and whether the aside is a supported format or not.

[nacin]

(In [17240]) Don't check for post format support when registering the post format taxonomy. fixes #16146.