Add benchmarks: Update, Get Secondary Key, and Concurrent operations

[vincent-herlemont]

Currently, the benchmarks cover only a small part of what the database can do. It is necessary to add the missing benchmarks; the ones that come to mind are update, get secondary key, and concurrent operations.

👉 Feel free to propose other benchmark ideas

Note: Create separate MRs for each benchmark

TODO

• update
• get secondary key
• concurrent operations (insert / update / delete / read)