Adding meta data for level height and altitude in LFRic diagnostics

### Are there any linked Issues or Pull Requests?

_No response_

### Brief description

Currently, LFRic diagnostics on model levels are output with the model level number (full or half levels) as the only descriptor of the vertical coordinates. The aim of this issue would be to add further meta data so that the level height and altitude are also specified.

### Further details of the issue.

To calculate the height above sea level (z), the following formula is needed:
z(n,k,j,i) = a(k) + b(k)*orog(n,j,i)
the model level number (k), level height (a), called the 'atmospheric_hybrid_height_coordinate', and a dimensionless coordinate, b, which is level dependent.

In the UM, b is stored as sigma, and is defined as C(k) in appendix A [umdp_F03.pdf](https://upgraded-adventure-jznrmqp.pages.github.io/papers/umdp_F03.pdf).

Details of representing this in a CF netCDF file are given here:
https://cfconventions.org/Data/cf-conventions/cf-conventions-1.13/cf-conventions.html#atmosphere-hybrid-height-coordinate