[wgpu-core] Replace usage of `PreHashedMap` with `FastHashMap`

[jamienicol]

Connections Fixes #6373

Description PreHashedMap was introduced as a performance optimization. It is, however, potentially unsound as it cannot distinguish between keys that are not equal yet have the same hash. This patch replaces its usage with a simple FastHashMap, which should be good enough. If this is found to cause real life performance issues down the line then we can figure out a better solution.

Testing cargo xtask test passes

Checklist

• [x] Run cargo fmt.
• [x] Run taplo format.
• [x] Run cargo clippy. If applicable, add:
  • [x] --target wasm32-unknown-unknown
  • [x] --target wasm32-unknown-emscripten
• [x] Run cargo xtask test to run tests.
• [x] Add change to CHANGELOG.md. See simple instructions inside file.

[ErichDonGubler]

@gfx-rs/wgpu: I'm not sure if we need a CHANGELOG entry here. Might be worth nothing as a General bug fix? 🤔

[Wumpf]

yeah would be nice to have it listed as a bugfix!

[jamienicol]

Added the changelog entry (and consolidated the duplicated General categories while I was there)

[ErichDonGubler]

Just needs conflicts resolved, and auto-merge should do the rest.

[jamienicol]

Just needs conflicts resolved, and auto-merge should do the rest.

done

and consolidated the duplicated General categories while I was there

heh, this was already done I just hadn't rebased