for-each-ref: load config earlier

In most commands we load config before parsing command line options, since it lets the latter override the former with a simple variable assignment. In the case of for-each-ref, though, we do it in the reverse order. This is OK with the current code, since there's no interaction between the config and command-line options. However, as the ref-filter code starts to care about config during verify_ref_format(), we'll want to make sure the config is loaded. Let's bump the config to the usual spot near the top of the function. We can drop the comment there; it's impossible to keep a "why we load the config" comment like this up to date with every config option we might be interested in. And indeed, it's already stale; we'd care about core.abbrev, for instance, when %(objectname:short) is used. Signed-off-by: Jeff King <peff@peff.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>