feat: Implementation of Generic EventController

[Addy1317]

[Assignment] Implementation of Generic Event Controller
[TASKS]
Implement Generic Event Controller class in Event Controller
Create a generic EventController for OnKeyPickedUp inside EventService

[Addy1317]

[Assignment] Improving UI logic
[TASKS]
Remove the serialised reference of GameViewUI and use the event listener to write custom logic.
Invoke OnKeyPickedUp in KeyView.

[Addy1317]

[Assignment] Adding OnKeyPickedUp Listener in PlayerController
[TASKS]
Add Listener of OnKeyPickedUp in PlayerController
Increment keys in PlayerController