Use `hashbrown::HashTable` instead of `RawTable` #404

Job	Run time
miri	4m 41s
Check MSRV and minimal-versions	1m 16s
nostd_build (1.63.0, thumbv6m-none-eabi)	1m 0s
clippy	18s
nostd_build (stable, thumbv6m-none-eabi)	8s
tests (1.63.0)	1m 44s
tests (stable, arbitrary)	37s
tests (stable, quickcheck)	48s
tests (stable, rayon)	42s
tests (stable, rustc-rayon)	40s
tests (stable, serde)	40s
tests (stable, borsh)	35s
tests (stable, std)	35s
tests (beta)	45s
tests (nightly, test build benchmarks)	36s
Success	1s
	15m 6s

Provide feedback