Update the iasi test file with two new reference datasets

[mikecooke77]

Description

This PR updates the iasi_metopb_obs_2021011500.nc4 test file to include TesReference/skinTemperature_onedvar and TestReference/skinTemperature_onedvar_biasTskin. These new arrays are used when testing the output from the files for the ufo_test_tier1_test_ufo_iasi_rttov_ops_qc_rttovonedvarcheck ctest in ufo.

Issue(s) addressed

None specifically raised.

Dependencies

Can be merged before the ufo associated PR at:

• [ ] https://github.com/JCSDA-internal/ufo/pull/3166

Impact

None

Checklist

• [x] I have performed a self-review of my own code
• [x] I have made corresponding changes to the documentation. Updated documentation linked as a dependency.
• [x] I have run the unit tests before creating the PR