Add support for IGCSInjector

[frostworx]

copy/paste of the (wip & offline) stl IGCSInjector wiki:

IGCSInjector

NOT COMMITTED YET

IGCSInjector is a tool, which is able to inject a dll into a running exe.
The main purpose of the tool is to manipulate the game-internal camera system with own settings.
More info and camera-settings for multiple games can be found on the InjectableGenericCameraSystem project page.

Injecting dlls won't work with every game or could lead to a ban (afaik mostly multiplayer), so be careful with injecting!

When enabling USEIGCS per game in Game Menu, stl

• automatically downloads IGCSInjector from the project page and extracts it
• copies the IGCSInjector exe into the game directory
• creates an initial IGCSInjector.ini in the game directory and automatically configures the game executable as exe to be injected.
  (when using UUUSEIGCS stl tries to find a -Win64-Shipping.exe in the game directory instead first)
• if no dll is defined in IGCSInjector.ini yet at all, or the defined one is not available in the game directory, a filerequester automatically opens.
  the selected dll will be copied into the game directory then and added/updated in the IGCSInjector.ini
• the IGCSInjector will wait for the game exe and wait optionally another IGCSWAIT seconds (configurable in Game Menu as well) and then will start the injection

If available and if USEIGCS or UUUSEIGCS is enabled, the IGCSInjector.ini can be also opened directly from the Editor Menu
(this is especially useful, if the dll is supposed to be injected into a different exe, instead of the initial game executable)

IGCSInjector is also able to inject other dlls into a game exe.
One of them is the UniversalUE4Unlocker dll, which *(re-)*enables the dev console in UE4 games.

[frostworx]

Added in release v6.13