soroban-rpc: Benchmark simulateTransaction endpoint

[2opremio]

We expect the simulateTransaction endpoint to be pretty expensive. Namely because:

• It accesses the ledger storage (sqlite-based) multiple times
• It crosses the Go<->Rust boundary multiple times

We already have a few ideas on how to optimize the code (use a write-through cache for the configuration ledger entries, optimize the data serialization stellar/stellar-rpc#49 etc ...) but we should first have a rough idea about how expensive the endpoint is, and where are the bottlenecks.

To do so, it would be interesting to have a benchmark. Such a benchmark is going to be challenging due to the use of CGO and Go<->Rust interfacing so we need to investigate how to carry it out.

A couple of things to take into account:

• Since IO (DB-access) is involved we should probably benchmark the wall-clock time.
• Obtaining the CPU bottlenecks of both Go and Rust simultaneously is likely to be pretty hard.

[2opremio]

Here’s an interesting pointer https://groups.google.com/g/golang-nuts/c/CKr1sGrTk98

It may be worth giving https://github.com/ianlancetaylor/cgosymbolizer a try

[2opremio]

I created a benchmark which is probably enough for now