Replace `camera_coordinates_to_xyz_mm` and `_project_xyz_to_xy` with derived axes

[DominicOram]

Following DiamondLightSource/dodal#1215 we now have a derived axis for the movement of a gonio in an OAV plane. We're currently redoing this same maths in other places in Hyperion, specifically:

• camera_coordinates_to_xyz_mm
• _project_xyz_to_xy

We should instead be able to add a similar derived signal to the smargon and use it in these places.

Acceptance Criteria

• Logic for calculating OAV coordinates in based on smargon co-ordinates are all done in the device