DiskBBQ - Panama support for 2 bit index to 4 bit query asymmetric quantization

[tteofili]

this adds PanamaVector support for 2-bit indexed vs 4-bit query asymmetric quantization in DiskBBQ (see #136989), which leads to same recall but much higher QPS / lower latency.

baseline (PanamaVector disabled for 2to4bits asymmetric)

index_name       index_type  visit_percentage(%)  latency(ms)  net_cpu_time(ms)  avg_cpu_count     QPS  recall    visited  filter_selectivity
---------------  ----------  -------------------  -----------  ----------------  -------------  ------  ------  ---------  ------------------  
wiki1024en.docs         ivf                 1.00         1.13              3.91           3.46  884.96    0.81   12966.31                1.00
wiki1024en.docs         ivf                 5.00         3.87             12.15           3.14  258.40    0.88   52983.88                1.00
wiki1024en.docs         ivf                10.00         8.42             24.31           2.89  118.76    0.88  102677.22                1.00
wiki1024en.docs         ivf                30.00        21.28             65.92           3.10   46.99    0.88  302296.72                1.00
wiki1024en.docs         ivf                50.00        34.13            107.93           3.16   29.30    0.88  501898.25                1.00
wiki1024en.docs         ivf                70.00        46.41            149.06           3.21   21.55    0.88  701366.05                1.00
wiki1024en.docs         ivf               100.00        65.58            210.46           3.21   15.25    0.88  998000.00                1.00

candidate

index_name       index_type  visit_percentage(%)  latency(ms)  net_cpu_time(ms)  avg_cpu_count      QPS  recall    visited  filter_selectivity
---------------  ----------  -------------------  -----------  ----------------  -------------  -------  ------  ---------  ------------------  
wiki1024en.docs         ivf                 1.00         0.47              1.87           3.98  2127.66    0.82   13224.37                1.00
wiki1024en.docs         ivf                 5.00         0.74              2.56           3.46  1351.35    0.87   52628.29                1.00
wiki1024en.docs         ivf                10.00         1.34              4.50           3.36   746.27    0.88  102770.24                1.00
wiki1024en.docs         ivf                30.00         3.39             11.78           3.47   294.99    0.88  302209.45                1.00
wiki1024en.docs         ivf                50.00         5.54             19.23           3.47   180.51    0.88  501835.49                1.00
wiki1024en.docs         ivf                70.00         8.10             26.84           3.31   123.46    0.89  701308.09                1.00
wiki1024en.docs         ivf               100.00        11.40             38.40           3.37    87.72    0.89  997999.00                1.00

this is on top of some changes in #137510

[elasticsearchmachine]

Pinging @elastic/es-search-relevance (Team:Search Relevance)

[john-wagster]

lgtm