Rename non-kebab case crates to kebab-case

[Veykril]

Basically all crates but rust-analyzer and vfs-notify are currently snake_cased. This is inconsistent and the concensus seems to be in favor of kebab-case for them.

https://rust-lang.zulipchat.com/#narrow/stream/185405-t-compiler.2Frust-analyzer/topic/crate.20naming.20conventions

[randomicon00]

Hi @Veykril,
Is this up for grabs? First time contributor but I would love to give it a try.

[lnicola]

It's yours.