heroic{,-unwrapped}: 2.22.0 -> 2.22.1; use nixpkgs legendary-gl

Changelog:
https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher/releases/tag/v2.22.1
Diff:
https://github.com/Heroic-Games-Launcher/HeroicGamesLauncher/compare/v2.22.0...v2.22.1

pin electron version
use nixpkgs `legendary-gl`

Co-authored-by: Keenan Weaver <keenanweaver@protonmail.com>