Issue with 32 bit compilation in coupled interface

### Version

main

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

_No response_

### What happened?

In coupler_update_prognostics_mod.X90 the JULES variable rhosnow is used. This is defined in JULES as 64 bit but the other variables in the calculation may be 32 bit if single precision is used. To protect against this a copy of the variable is needed at the working precision of LFRic.

### Relevant log output

```shell

```