Add new GDR-G variables to all data sets

[remkos]

Create a script to add all the new GDR-G variables to a satellite mission in RADS. This includes:

• FES2022 (Implement FES2022 #200)
• MSS DTU21 (Implement MSS_Hybrid-SIO-CLS-DTU-2023 and MSS_DTU21 #201)
• MSS Hybrid 2023 (Implement MSS_Hybrid-SIO-CLS-DTU-2023 and MSS_DTU21 #201, Switching reference mean sea surface #174)

En passant, we pick up some of the other updates that have not been applied to all mission data:

• FES2014 (FES2014 values wrong on recent data #205)
• SRTM15 (Implement new STRM15 version #203)
• OISST v2.1 (NOAA OI SST V2 changed to high-resolution #187)
• Pole tide (Update pole tide to latest IERS conventions #176)
• ERA5 (ERA5 replacing ERA-interim #142)

Also, we can add a few more things that came in recently

• GSFC Std2400 orbits (Add alt_std2400 to reference missions #209)
• Update the DAC (Add DAC TUGO #210)

And then

• Remove obsolete variables (Remove obsolete variables #208)

Then run that script for all the following missions:

• 3a
• 3b
• 6a.hr
• 6a.lr
• c2
• e1
• e2
• g1
• gs
• j1
• j2
• j3
• n1
• pn
• sa
• sw
• tx