Add Keen Game's engine

[MichaelHinrichs]

SteamDB app page links to a few games using this

https://steamdb.info/app/374040/ https://steamdb.info/app/1203620/

Brief explanation of the change

Identify Keen Games kfc_data and kfc_dir file types.

[SteamDB-Tracker]

After running changed rules in this pull request (this bot only tests rules.ini changes):

Changed technologies: Engine.Keen_Games_Engine

These apps now match: (4) 374040 1203620 2278520 2614110

Please confirm that all these changed apps are correct.

[Lifeismana]

not used by enough apps