Diagnostic checking in rose-stem

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

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### Brief description

Currently, the lfric_atm rose-stem suite only checks the "known good output" (KGO) pertinent to model evolution, defined by global checksums on the 5 main prognostic variables in the model (wind, temperature, pressure, density, moist mass mixing ratios).

This is not sufficient testing to ensure that the behaviour of the modelling system is preserved. None of these 5 variables are used for driving the data assimilation system, downstream products or evaluating the skill of the model - these processes are entirely reliant on diagnostic output constructed within the model. Therefore, rose-stem needs to check that this diagnostic output is preserved. It would be entirely possible for the current KGO checks to pass but diagnostic output to be altered in a way that could significantly (negatively) impact our ability to run and use the model.

Therefore rose-stem checks need adding for diagnostic output files. Usually (e.g. in the UM and standalone LFRic suites) this process is done with "rose-ana" tasks, an example of which can be seen here: https://code.metoffice.gov.uk/trac/roses-u/browser/d/i/6/2/0/trunk/app/rose_ana_restart/rose-app.conf

This uses "nccmp" to compare LFRic output files. Ideally the exclude list should be empty, although it is possible that some diagnostics do not currently contain reproducible missing data in areas where the diagnostic is invalid (e.g. land temperature over the sea). If during adding the tests, we find diagnostics for which this is the case, they should be added to the exclude list and separate PRs should populate the missing data correctly and remove them from the exclude list.

The output files which should be checked are those files produced by the following xml files:
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_gal_clim.xml - standard diagnostic output from climate models for driving auto-assess
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_gal_nwp.xml - standard diagnostic output from NWP case studies for driving TRUI analysis
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_ls_and_jedi.xml - standard diagnostic output from NWP jobs for driving JADA data-assimilation
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_name.xml - standard diagnostic output from NWP suite for driving NAME dispersion model
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_oper_nwp_gl.xml - standard diagnostic output from operational suite for driving downstream products
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_ral.xml - standard diagnostic output from regional modelling for driving CSET analysis
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_ral_ls_and_jedi.xml - prototype output from regional modelling for driving regional JADA
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_var_ops.xml - standard diagnostic output from NWP trials for driving OPS and VAR
* https://github.com/MetOffice/lfric_apps/blob/main/rose-stem/app/lfric_atm/file/file_def_diags_ver.xml - standard output from NWP jobs for verification

### Further details of the issue.

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