hyprland: add option for recommended environment variables

[andresilva]

Description

Adds an option to enable recommended environment variables for wayland session, right now just NIXOS_OZONE_WL.

Fixes #4486.

Checklist

• Change is backwards compatible.

• Code formatted with ./format.

• Code tested through nix-shell --pure tests -A run.all or nix develop --ignore-environment .#all using Flakes.

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Maintainer CC

@fufexan

[andresilva]

I just found the discussion in the original PR that introduced this module around this option (#3837 (comment)), so I guess this won't be merged. Maybe #4486 should be closed as no fix then (i.e. the user should explicitly enable the environment variable).