Initial commit for GatchaActionHandler

[Tom2096]

- register GatchaActionHandler in GmeController_Handlers.cpp
- currently returns a hard-coded unit with a hard-coded userUnitID

[arves100]

Hello, do you think you can refactor the code in preparation for #10?
So like firstly add a new definition for the packet inside https://github.com/decompfrontier/packet-generator/tree/main/data/net and then adapt the code for the new handlers?

[Seltraeh]

Hello, do you think you can refactor the code in preparation for #10? So like firstly add a new definition for the packet inside https://github.com/decompfrontier/packet-generator/tree/main/data/net and then adapt the code for the new handlers?

If all goes well with the testing I do tonight, all handlers and responses should have a template. This will effectively remove all handlers that were perceived as tedious work to reverse, and allow us to focus more on parsing their responses should an action crash the game.

@arves100 Will this effect the packet generator's creation timeline? I breifly looked at the generator and it seems like an additional way to handle the request-response workflow between the game client and server.