write benchmarks and performance tests

[lrlna]

Things that would be very interesting to see:

• memory usage
• heap usage
• latency?? Maybe??

[Miaxos]

👋 Very interested by these tests for the parser, so I hope you don't mind I participate:

It would be interesting to compare it to other existing parsers where we compare the speed between parsers to parse queries/schema at cold & hot start.

For perfomance tests I think https://docs.rs/criterion/0.3.5/criterion/index.html would be a really good fit for those tests.

[lrlna]

@Miaxos no problem!

We thought about this a bunch, and don't necessarily want to make this a competition with other parsers in the ecosystem (thus the title change of this issue). We'll definitely write benchmarks, but they won't be "apollo-rs performs better/worse than x". Criterion is definitely the standard choice for something like this :)