Add new camera focus system for Yarn

[Demigiant]

Add two separate methods:

1. FocusOn(Transform lookAtTarget, Transform origin = null) aka Yarn's camera_focus
   Moves to first origin's position and focuses on lookAt target.
   Origin can be NULL in which case the camera stays where it is and only does the lookAt.
2. ResetFocus() aka Yarn's camera_reset
   Resets focus to cat
3. For the future: ShowMap() aka Yarn's camera_map
   Shows the map, without evidencing anything special

That can be called at any time during dialogue

[Demigiant]

Done.

There are two ways of calling the methods:

1. From InteractionManager.I, which also hides the UI when focusing and shows it again when the focus is reset
2. From CameraManager.I, which only controls the camera and ignores the UI

via InteractionManager.I

Hides the UI and focuses the camera to look at a specific target and with an optional specific origin
public void FocusCameraOn(Transform target, Transform origin = null)

Shows the UI and resets the eventually active camera focus
public void ResetCameraFocus()

via CameraManager.I

Focuses the camera to look at a specific target and with an optional specific origin
public void FocusOn(Transform lookAtTarget, Transform origin = null)

Resets the eventually active camera focus
public void ResetFocus()

IMPORTANT

For now the camera maintains the previous behaviour, which automatically resets a focus when "ACT" is pressed. If/when you want to disable this behaviour, comment out this line in InteractionManager.cs: