[boost] [utility][detail] Moving binary_search_test from utility to detail.

Hi, I've created a couple of pull requests to move this test from utility to detail, as the header it's testing is in detail. I guess it's in utility because there weren't any detail unit tests when it was created. If there are no objections I'll merge them this weekend. https://github.com/boostorg/utility/pull/9 https://github.com/boostorg/detail/pull/2 Daniel