feat: move to rustc fx hashmap

[benfdking]

mostly just to test the benchmark job but this improves parsing performance by 17% on long.

[benfdking]

Works but can't comment from a fork

[georgesittas]

@tobymao waiting for you to take a look here before merging. Even though rustc-hash is under dependencies, my understanding is that this should be fine because:

1. It is used in rustc itself, see repo.
2. We pre-compile the rust tokenizer and ship the various binaries when releasing sqlglotrs, so users shouldn't encounter any dependency issues. @benfdking to verify. Could there be linking issues with this library at runtime?

[benfdking]

I don't expect this to affect anything. For those who don't have prebuilt binaries, python will build it with cargo and there it is done without any user intervention so no more invasive than what's there already.