Implemented QOL features for SteamRPC

[angelolz]

Here's a list of changes and additions I made:

• Added config.js to be the place to change config, so that it's separated from the source code
• Instead of using the SteamRPC default client ID, game profiles can specify their own client ID which allows the user's presence to say "Playing " instead of always saying "Playing Steam"
  • If the profile does not have a clientID, SteamRPC's client ID will be used as a fallback.
• Destroyed the rich presence when the user is no longer in game. This fixes #3.
• Implemented startTimestamp support so that profiles can make use of it.
  • Currently, I'm not sure how to implement endTimestamp as well, but I figured that the most common use case for timestamps in rich presence for games is to show how long you've been in a match/game/mission/etc..

[Crementif]

Nice QoL stuff! I'll try to check these tomorrow, but feel free to remind me if I forget haha.