The plugin apply_yaml_config_fn dispatch loop only ran when a top-level
platform block (e.g. `discord:`) existed. Configs that defined a platform
only under `platforms.<name>` or `gateway.platforms.<name>` skipped the
hook, so `platforms.discord.extra.allow_from` never reached
DISCORD_ALLOWED_USERS. Fall back to those nested blocks when the top-level
one is absent.
Also map byquenox@gmail.com -> Que0x for the salvaged commits.