Re-enable the GameTooltip hooks for Classic (Era) clients

[rdw-software]

See https://github.com/WowRarity/Rarity/pull/816 - they're currently disabled on Classic realms. Cataclysm seems to use the new API and should be working. The problem might fix itself when Blizzard ports the retail APIs to their classic client.

Could integrate the old tooltip hooks in the meantime?

Update: It's been reported on Discord that Cataclysm is not, in fact, working. Needs looking into as well.