Linuxgsm: Improved Workshop support

[dgibbs64]

Is your feature request related to a problem? Please describe.
Several game servers support the use of Steam Workshop, however, LinuxGSM is currently quite limited in both supporting this and documentation. Since I do not know much about workshop I require assistance and documentation of various game servers that support workshop to allow better integration.

Workshop Supported Games

ARMA 3
CS:GO
Rust
Hurtworld
7 Days to Die
Garrys Mod
Starbound
Source engine games (SourceMod)

[0xlord]

ARMA 3 with the help of a python script: https://forums.bohemia.net/forums/topic/212534-arma-3-linux-server-and-mod-updater-workshop/

Bohemia Interactive Forums

Arma 3 Linux server and mod updater (workshop)

Arma 3 Linux server and mod updater (workshop) A python script that updates your server and mods. Just edit the variables in the "Configuration" regio...

[dgibbs64]

relates to #1623
relates to #960

[JediNarwals]

I have made a working mod downloader and installer for Arma 3. However, it is not currently integrated with the main LinuxGSM files because it requires manual file updating. If you update LinuxGSM with this file in the functions it will update to the default blank. So it would need to be your own branch of the file.

If you would like to see my version, you can find it here.