UT[bmqc]: get rid of libbenchmark, add benchmarks

[678098]

Benchmarks (darwin)

                    Map::insert | Elements | Time (ns) | Per op (ns)
====================================================================
bmqc::OrderedHashMapWithHistory |  5000000 | 903171583 |         180
           bmqc::OrderedHashMap |  5000000 | 325063542 |          65
             bsl::unordered_map |  5000000 | 588688667 |         117

                     Map::erase | Elements | Time (ns) | Per op (ns)
====================================================================
bmqc::OrderedHashMapWithHistory |  5000000 | 410941709 |          82
           bmqc::OrderedHashMap |  5000000 | 217761750 |          43
             bsl::unordered_map |  5000000 | 319221833 |          63

                      Map::find | Elements | Time (ns) | Per op (ns)
====================================================================
bmqc::OrderedHashMapWithHistory |  5000000 | 116258417 |          23
           bmqc::OrderedHashMap |  5000000 |  68910958 |          13
             bsl::unordered_map |  5000000 | 174589125 |          34

Surprisingly, bmqc::OrderedHashMap greatly outperforms bsl::unordered_map.
bmqc::OrderedHashMapWithHistory is mostly slower than bsl::unordered_map.