Added rd_lobby_query_servers convar (default 0 until the problem with the Steam API is fixed) to disable server list queries, which are currently not being properly filtered to just Alien Swarm: Reactive Drop servers by the Steamworks API.

• Note: This means that HoIAF servers are not labelled in-game currently. Progress is still tracked, and HoIAF servers can be found via the Steam Client "Game Servers" list or a website that has a server list, such as https://serverlist.reactivedrop.com/server-list, neither of which appear to be affected by the filtering issue.

Reduced the performance impact of the Steam Workshop download progress widget.