make friends_ids optional list[str]

[RheingoldRiver]

if friend cog isn't loaded we're sending None

(or we could just send empty list if friend cog isn't loaded)

https://github.com/TsubakiBotPad/pad-cogs/blob/master/padinfo/padinfo.py#L153
https://github.com/TsubakiBotPad/discord-menu/blob/main/discordmenu/reaction_filter.py#L82

[RheingoldRiver]

(doesn't matter for us obviously but it makes the process to setup for people who are contributing code a lot harder if they have to load misc-cogs stuff to start doing padinfo stuff)