CMIP7: UKCM2 processor apply_SI3_U_coordinates

[mo-laurenboon]

In order to produce some variables, a processor is required to apply the correct coordinates.

The variables that currently require this processor (as per their mapping information) are as follows:

Grid	Variable	Mapping Information
mip_convert_ind_ocean-native-icemod	siu_tavg-u-hxy-si	1694
mip_convert_inm_ocean-native-icemod	siu_tavg-u-hxy-si	1790
mip_convert_inm_ocean-native-icemod	sistrxdtop_tavg-u-hxy-si	1781
mip_convert_inm_ocean-native-icemod	sistrydtop_tavg-u-hxy-si	1783
mip_convert_inm_ocean-native-icemod	siforceintstrx_tavg-u-hxy-si	1741
mip_convert_inm_ocean-native-icemod	siforcetiltx_tavg-u-hxy-si	1743