adopt actix-ws crate

[robjtede]

PR Type

New Crate

PR Checklist

• [x] Tests for the changes have been added / updated.
• [x] Documentation comments have been added / updated.
• [x] A changelog entry has been made for the appropriate packages.
• [x] Format code with the nightly rustfmt (cargo +nightly fmt).

Overview

As discussed with @asonix on Discord, we're adopting the actix-ws crate.