Add Steam Launcher plugin

[hyunwoo312]

Adds Steam Launcher, a native C# Steam plugin.

• Repo: https://github.com/hyunwoo312/steam-launcher
• v1.0.0 release: https://github.com/hyunwoo312/steam-launcher/releases/tag/v1.0.0
• Action keyword: st

Features: launch installed games, search the Steam store, list/filter friends with favorites, switch active Steam account, set persona status, find shared multiplayer games with a friend, verify game integrity, open Steam settings/downloads. API key encrypted with Windows DPAPI.

[deefrawley]

There are already 4 other plugins that can launch steam games and switch steam accounts. Did you consider contributing to them rather than creating a fifth? What does your plugin do that those don't?

[hyunwoo312]

Well to be fair, I only saw Steam Search and SteamFlow to be overlaps. I have been using Steam Search for more than a year and felt maybe I could add something then found out about SteamFlow, but every keyword command execution came with noticeable lag/delay. I assumed that's because the plugin was written in python. It definitely didn't sound right to randomly message them and suggest rewriting either of their plugin in C#, so I just made one from scratch.

If you do ask about what's different from them, mine does have a couple more keyword commands that involve steam friends, but at the end of the day authors of the other plugins can simply add similar features themselves too. My main motif for this plugin was having the plugin be written in C# for performance and adding some new keyword commands while doing so, and if you do find this plugin an unnecessary duplicate to the current plugin list, please feel free to close the pull request.