Add follow/unfollow official game group option

[blue-lightning]

Example: OC ask people to follow their official game group in this GA:
https://simplo.gg/index.php?giveaway=free-steam-key-athopiu

[Citrinate]

Looked into it, and this isn't a trivial thing to add. Seeing as there's only been 1 of these, it's hard to justify the amount of work this would require.