Make variable names conform for opsinputs

[mo-keithstewart]

Description

This is the work required for issue #162 for changes to the variable names so that there is more consistency in the system, as defined in this spreadsheet

The following fields are updated: theta >> potential_temperature cloud_area_fraction_in_atmosphere_layer >> cloud_volume_fraction_in_atmosphere_layer liquid_cloud_fraction >> liquid_cloud_volume_fraction_in_atmosphere_layer frozen_cloud_fraction >> ice_cloud_volume_fraction_in_atmosphere_layer

This fixes an issue we currently have with variable mismatch between different parts of the system.

Acceptance Criteria (Definition of Done)

Test builds and run

Test output is here.

Dependencies

Requires changes to ops-um-jedi, ufo, ufo-data, lfric-lite-jedi, saber, vader and sith

• [x] waiting on ops-um-jedi: #187
• [x] waiting on ufo: ufo: #2719
• [x] waiting on ufo-data: #312
• [x] waiting on lfric-lite-jedi: #243
• [x] waiting on saber: #502
• [x] waiting on vader: #162
• [x] waiting on sith: #174

[MarekWlasak]

@mo-keithstewart - have you tried the new varobs and cx in VAR?

[mo-keithstewart]

@MarekWlasak - I have run these variable name changes on the latest version of sith and compared the develop version of the code with my changes. This should test these changes with VAR.