Benchmark for C++ PDQ index

[16BitNarwhal]

Summary

Resolve #1697

C++ query benchmark program for brute force linear scan and mih (pdq/cpp/index/mih.h)
Benchmark implementation located in pdq/cpp/bin/benchmark-query.cpp
Benchmark results in pdq/cpp/index/README.md

To run:

cd pdq/cpp
make benchmark-query
./benchmark-query

Sample results (ran on Ubuntu 24.04.1 LTS, Intel Core i7-14700KF with 20 cores, 28 threads, 64GB RAM):

$ ./benchmark-query -m linear
METHOD: Linear query
QUERY COUNT:             1000
INDEX COUNT:             10000
TOTAL MATCH COUNT:       1000
TOTAL QUERY SECONDS:     0.258911
SECONDS PER QUERY:       0.000259