Add summary scripts for vector index build and search benchmarks

- Introduced `summarize_11_vector_index_build_matrix.sh` to summarize results from vector index build benchmarks, generating JSON and Markdown summary files.
- Introduced `summarize_12_vector_search_matrix.sh` to summarize results from vector search benchmarks, generating JSON and Markdown summary files.
- Both scripts include functionality to handle datasets, extract parameters, and format metrics for better readability.

Author: tae898